My rooster has always had the reddest comb. Now it is light pink. He is also acting really mean to the hens but was a sweet guy, who shared his treats. He chases the hens around and wont let them eat. We thought we would give him a little to get better. But he has been like this for over a month. He is not molting has no mites either.
One died yesterday she had symptoms similar to mareks.
Looking at his tail feathers are you sure he's not molting?his crop seems to be working perfectly fine, it is always full. He has seemed to lose s lot of weight though he is only about 5 pounds, he was 8ish pounds. But he has been eating a lot.
You may want to check him over for pin feathers coming in, but be gentle.
It can take a while to finish molt. I normally don't separate out hens, but I will a rooster if they are struggling. I noticed mine changed during molt and didn't want to share food or treats.
I gave mine soaked feed with a little buttermilk and added B-Complex 3-4 times a week. Give chick starter or an all flock feed for the rooster if possible during molt or add some protein like egg, meat or fish.
Sorry you lost a hen(?) recently. Was she new to the flock? Marek's might be a possibility if that was the cause, but I would be looking at molt and lice/mites. Mites generally are seen at night, so go out with a flashlight and inspect him then.