I had a 2 1/2 year old snake, Bread, pass away very suddenly a few days ago after being seemingly healthy. I took him to a vet when my snake started seizing/stroking out and gasping for air... and the vet looked him over, in his mouth, vent, on his stomach, real close at his nose and eyes, just about every inch of him and said he seemed healthy and didn't know why he died so suddenly.. just maybe because he was so unique externally, that he could be just as unique on the inside..
I took his twin sister, Butter, to the same vet to have her checked out, she weighs 5.5 oz (he was shorter and smaller, more around 4.8 oz, so they weren't undernurished), and he checked her out just the same and said she seemed healthy too... With that in mind, and Bread's sudden passing, I want to learn about snake diseases and illnesses so I can prevent or at least spot an issue before something like this happens again.
Neither snake showed any signs of any infections... and no parasites either, there is the possibility of perhaps a viral issue, but there isn't any "blushing", red, or inflamed scales on Butter, and I didn't notice any on Bread. They were both off feed for 4 weeks, and on the 4th week Bread died. They are sexually mature, and I was getting them in the "mood" to breed, but then tragedy occured.

He asked me a pleathera of questions on husbandry/feeding/stool normality/and sexual maturity, to which I responded honestly, and he said I was doing everything perfectly and everything I was doing and seeing/observing was normal... but he did ask me if I used any vitamin supplements while feeding, and I said I used to when they were younger... and he suggested that perhaps I should give them vitamin supplements occasionaly, should I take his advice? I don't think that could hurt, right?

Most importantly, I would like a TRUSTED, complete, detailed list of snake diseases and illnesses, and some input on what could of happened to Bread.