Cold tank and breathing noise sounds like RI.
I wouldn't be quite as harsh about going to a pet store person since I personally know one that is very knowledgeable. However, I definately concur - see a herp vet. Then, if you are sure your pet store guy is experienced, you can use him as an additional resource. Pet store guys are more accessible than vets.
For example, my snake got RI from having cold spots in his cage. I went to a vet and eventually ended up with a handful of syringes and directions to give my snake shots! The store I got my BP from had three people all with vastly more experience giving snakes shots than I had - and that came in real handy because they were happy to help me out. I let them do the shots and just helped holding him. Man, its amazing how tough it is to restrain a snake.