I know you're worried, but this is what I'd do.. if you can't get a sample to the vet tomorrow then give him baths each day, if he's still having diarrhea shorten them, aim for 7-8 minutes if you do one each day.. that'll keep him
hydrated.. if he's still not eating try to offer a little dish of greens.. use shredded collard, mustard or turnip greens with a bit of shredded squash in there.. maybe he may take to it, but if you ever have a chance to get him to eat it on a regular basis doesn't hurt to try now.. hold a bunch up to his snout and let him smell it, place the dish in the cool end.... and leave him alone and see what happens.. you can also get unsweetened baby jar food, try apple sauce or even a chicken flavor and mix a bit if his calcium in it and offer it by a syringe (the kind with no needle that you use for kids medicines, if you can't find one in the pharmacy ask the pharmacist for a medicine dropper and he'll know what you mean).. don't force feed, but squeeze out a bit on the bottom of his snout where his mouth opens and he may lick it off, let him do that as much as you can.. if he does take a significant amount and still is having diarrhea lay off the
bath that day so you don't over do it.. you can also in the meantime if you want him to eat, at petco they have calci-worms which are small, similar to the Phoenix worms I mentioned before, if they don't have them they may have wax worms which are small, if he does take to those don't feed too many as once his appetite comes back he'll be stubborn to go back to crickets.. try those things and just do what you can to make him comfortable til you can have a sample analyzed..
Gina