I have a book called current therapy in exotic pet practice and all that has been mentioned above by everyone including me is very possible the full list of usual causes of this are GI disease, nematodiasis, MBD, gastric overload, intoxication (have you and your frog being having vodkas? Only kidding), hypocalcemia, impaction or obstruction.

I would say more common is impaction, MBD, and protozoa parasite. If it was parasites it would be salt baths rather than sugar.

So as you can see given most of the possibilities its hard for anyone to give a true diagnosis of this when just using pictures. If you cant get a vet my suggestion is to contact your local university they may have the ability to do a quick ultrasound for you.