Sorry I'm replying so late but i have been outside building a larger kennel/pen for the new baby turkeys. Ok, now let me try to answer all of your questions.....
What caused crooked neck? When my tom first got crooked neck, I spent MANY hours a day researching what could be wrong with him. This is some of the information that I read online.
http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/203404.htm
http://www.thepoultrysite.com/diseaseinfo/98/mycoplasma-meleagridis-infection-mm
Crooked Neck - A disease of turkeys thought to be due to airsacculitis caused by Mycoplasma meleagridis. A similar syndrome in Brown Leghorn chickens is due to an inherited defect.
Mycoplasma meleagridis infection is a widespread, egg-transmitted disease of turkeys found worldwide. The primary lesion in the progeny is airsacculitis. M meleagridis is thought to be a specific pathogen for turkeys, and the organism is commonly found in the respiratory and reproductive tracts. It has been eradicated in most basic breeder and many commercial flocks.
Signs
Reduced hatchability.
Slow growth.
Leg problems.
Stunting.
Mild respiratory problems.
Crooked necks.
Infected parents may be asymptomatic.
Treatment
Tylosin, spiramycin, tetracyclines, fluoroquinolones. Effort should be made to reduce dust and secondary infections.
In your post you said..............."
"There aren't any breathing difficulties or fowl pox or anything in my tom". "I've never held him or even touched him -- got him as an adult, and let him out of the box! He now lets me get within 3 feet without freaking out, but that's about as close as I ever get." Your tom could possibly have an upper respiratory problem that you cannot "hear" being as though you can only get within 3 feet of him. I thought the same thing about my tom. I didn't think that he had any breathing problems either until I caught him and listened to him breath. He did sound as if he had a bad cold and was congested. Sound like he needed to blow his nose. If I hadn't caught him and did a head to toe visual check and listened to him, I would have never known about the respiratory problem. I got my tom as an adult as well and no one can easily catch him. Myself and my male relative used a net to catch him.
Should you worm him again plus all the nutritional? I don't think that he has worms from what you said.
("His droppings look good -- normal (no wormy look or anything, just looks healthy). " I think he just has the crooked neck. If I were you, I would concentrate on what i suggested which leads to the next question.
What is Tylan 50? Tylan 50 is an antibiotic.
Where do you buy Tylan 50? You should be able to find it at any feed store. You may have to call around before you go out searching.
What would you be treating with it? I hope I understood this question. You should get a needle and give your turkey a shot in the chest. Well, that is what I did. He received an injection twice a day. The man at the feed store told me to put it in the tom's water but I didn't listen to him. I wanted the medication to work ASAP and giving a shot did it for me. The box of Tylan 50 that I have has on it "For Use in Cattle and Swine" but I read and the man at the feed store said that it was safe for Turkeys and it was.
Recovery time - After 2 days of hand feeding boiled eggs, squirting syringes of pedialtye and Enfamil Poly-Vi-Sol Multivitamins for infants and toddlers down my tom's throat, my turkey finally showed some signs of hope. He had been roosting on the ground with his head almost touching the ground with open wings. On the 2nd day and after 30 minutes of hand feeding him, he flew on the fence that he usually roosts on and went to sleep. On the 3rd day after hearing how congested he was, was when I went to the feed store to get the Tylan 50. After administering the shot and within 24 hours I saw great improvement! He was eating and drinking on his own. His neck was still crooked but was straightening up slowly but surely. I would say that within about 6 weeks, he was back to normal. The crooked neck was gone and it has never returned.
I hope that I have helped you out a little. I am definitely no Turkey expert and I know that there are a few turkey experts on BYC who may be able to add something that I missed.
People that I told about the crooked neck came over to see and was amazed to see the turkey looking that way. They just knew that he would die. After seeing him recover and seeing that his neck straightened out, they could not believe it. They were amazed. One older gentleman now comes to me with any and all chicken, duck, geese and turkey problems and looks for my input. He said that if I cured my turkey, then I must know what I'm doing.
. I just thanked him for the compliment and told him that the internet and BYC is where I learn.
One last thing. Please keep an eye on his food intake and water intake. Please dont assume that he is eating. Please know for sure either way. It is important to keep him fed and hydrated. If you have to hand feed him, then please do that. You may need help catching him and definitely need help giving him the injection. It took 2 people to give my tom his injection. He is HUGE! I'm a woman and i couldn't do it alone.
Many people told me to place him in an area away from the other animals so that they would not get infected with what he had. I didn't liste because I didn't want him to be confined and get depressed from not being with his girls and his other friends. Luckily, no other animals were infected. So, I don't know if you want to place him in an area alone or not. That's up to you but as I said, everyone told me to separate him from the rest of the flock.
Just a note before closing. You are in for some hard work that is time consuming. It was not easy for me at all but in the end it all worked out. He survived and is walking around the barnyard like the king that he is. I just went outside to take an update pic of him but I couldnt get a good pic because he is soooo busy strutting his stuff around his girl and his new baby turkeys.
Let me know if you have any other questions.
Keep us posted.
I just noticed that we have the same breed turkey. We both have a Bourbon Red Tom.