I have had quite a few with purple coloured combs, and unfortunately they have died. I am sure it is heart problems. But having said that, my pekin cockerel had a very funny looking comb on Sunday. I thought he was near the end, but, I put him in a hen coop on his own, and he has perked up, and so has his comb. I think all this wet weather had caused him to get cold and affect his circulation!!
Hopefully yours too will make a recovery.