My Grey Tree Frog had the same problem but he wasn't sick. He is 6 months old, had him since an egg. Well he was refusing to eat so I tried to feed him crickets but he wouldn't eat them. So I got flies and held the fly by its wing and it started buzzing and got my frog excired so he started to eat and he would ONLY eat flies for 2 weeks before I could get him to eat crickets. So try mixing up kinds of food you feed him. FYI- Flies are my frogs favorite so when I get them they are a treat for him. Hate growing maggots eeww but he enjoys them.