I can't help but wonder why on earth you didn't quarantine a new snake, especially a rescue, and most especially a boa ??!!

I know stress and a change on environment can bring about such behavior, but whether or not he is sick I can't tell you.

My best advice is this, he is your snake and you know him. If you don't think he's right, chances are he's not. A vet visit will go a long way towards easing your mind.

Gale