Give him time to digest his food. Remember their metabolism is slow and depending on age, he may not go every day. As far as his mouth being open, me and another member were discussing that with our panthers and have a theory. If you are feeding him really big HW, it seems that the cham will do that for some reason. Maybe he got too full to quick or has gas or something, LOL. Don't worry about it unless it's happening without feeding HW.