boa constrictor

Question
purchased a baby boa 2 weeks ago, after a few days discovered he had mites. been treating with Mite Away and thorough cleansing of everything.  Today he is very listless can hardly lift his head.  Advised he may be dehydrated.  soaked him for 2 hours seems a bit stronger but not right, his head still not strong.  do i  now need to take him to the vet?

Answer
I'd take him back to the pet store.  Has it eaten?  I hate to say this but what you describe sounds very serious.  I think a vet will be required, but I do not know if it will help.  Did he have the mites when you bought him?  If so, the pet store should make things right.