I'm sorry about your rooster.
Can you get some clearer, wet lit photos of him, his poop and his face?
Check inside his beak for any signs of canker and lesions.
Please look inside his ears for signs of pus and infection.
Does he have any lice or mites on the body? You will see crawling bugs on him, look around the head, face, under wings, top of tail and around the vent.
I do see that he has Scaly Leg Mites, you will want to treat those. Since he's not well, apply vaseline or NuStock cream to the legs/feet working the treatment of choice up and under the scales of the legs/feet.
He also has Wry Neck, this is a Neurological Symptom, some common causes are head/neck trauma, disease like Mareks and nutritional deficiency. Silkies sometimes seem to be more prone to having neurological issues.
I'd get him started in 400IU Vitamin E and 1/4 tablet B-Complex daily along with a small amount of egg to help with the uptake of E.
If possible, post the feed label of your feed. I do see pellets, but also quite other things in the feed bowl. He may be picking out the things he likes and not eating the pellets or other ingredients that would round out his diet, so he may be lacking in key nutrients.
You mentioned he gasps if he eats a wet mash, this is not ideal, so I'd be hesitant to feed a wet mash if he has difficulty managing it. (again, inspect the inside of the beak).
You may find that you need to change the type of feed to just a pellet or crumble. You don't mention where you are in the world, so it would be nice to have an idea if you are in the US or another country. If in the US you should be able to source a chick starter, all flock or similar feed that is in pellet or crumble form that he can eat dry.
I'll leave example photos below of Vitamin E and B-Complex so you know what to look for, these can be found at stores like Walmart, CVS, most groceries and online.
Scaly Leg Mites
