My rooster of five years died yesterday. He was combating some sort of respiratory problem for over two months with vet prescribed antibiotics/anti fungals. On Thursday I noticed his comb had started to pail in the inner areas and get dark in the outer areas. I took him to the vet again and he was afraid that he may have pox or marks since over two months of trying different antibiotics didn't help. I feel awful because at my last attempt to figure out what he was suffering from he died after getting to the vet. When he died I heard him gasp for air twice and then he started kicking his legs and flapping his wings uncontrollably. This experience was extremely traumatizing for me, as my chicken had been a great companion four five years. He was having trouble standing at the end, and at the last vet visit there was what looked like some bloody flem in his throat. He had a throat culture done and it came up with yeast and antibiotic resistant staff. It had gotten so bad that he had to be force fed. He was having a lot of trouble breathing, and standing yesterday, and the day before that he was taking short quick breaths. He was chocking and sneezing a lot when i started treatment, and he was a little lethargic. The weirdest thing is that a couple of weeks ago he started acting like himself, and that was when the throat swab came in and we started to treat the staff and yeast, he went downhill from there. I am glad he is no longer suffering, but I miss him. I refuse to send him in for a biopsy to get some answers, so I hoped I could get some help on here. My question is what do you think he could have died from? And do chickens often have spasms that bad before they die or after they are dead?