I would be cautious of something like Cryptosporidium. I had a male corn snake that started regurging constantly and he had been perfectly healthy before that. When he passed I had the vet to a necropsy on him and she found that this is what he had. It is highly contagious so if you have other snakes keep him away from them. Also you will want to use a bleach solution on any container that he has been in before putting any other reptiles in it. Unfortunately as far as i know there is no definitive test for it.