Dead corn snake

Question
Yesterday i had to have my 1 year old snow corn put to sleep, in the morning i found him having what i could only describe a fit of some sort (He was acting normally the night before) he was tensing up so much he was popping his bits out of his back end, he carried on like this most of the day but about 4pm ish he seemed to give up the will to live and just laid there twitching every now and then. When the vet looked at him she said she could not do anything for him and the best thing was for him to be put to sleep, i asked what could of caused this to happen all she said was possibly a bacterial infection (to be honest she did not seem to have a clue). I called the vet early morning but could not get an apointment until 6pm that evening as the vet was not available and sadly have no other reptile vets in this area.
I had concerns about his lack of growth over the last few  months as i he had mites about 1 month ago (brought in off a new snake, he was treated with Mite Off) i took him to my local reptile expert they looked him over and told me that if he was still eating & shedding i had nothing to worry about.
I have 2 other snakes (all kept in separate vivariums) and i am worried it may be contagious but the vet did not seem to be worried. Do you know of any disease, parasite etc that could cause such a rapid decline in a snakes health. Thanks.

Answer
Sorry to hear about your snake. I know how heartbreaking it can be.

It's really hard for me to say what might have caused it. In general, snakes seem to have rapid declines like you suggested whenever they get sick. The two things that popped into my head reading your description was that either the mites were carrying a disease that affected it, or else the mite spray that you used. I'm not familiar with Mite Off, but some sprays can cause neurological problems. As far as your other snakes, they have probably already been exposed since they were in the same room (I'm guessing), so just wait and see and hope for the best. There's not really much you can do, other than making sure that they are mite free.