Yup, sounds like the frog is impacted (severe constipation). Like Pluke said, soak him for 15-20 minutes in lukewarm De-Chlorinated water with a couple drops of honey in it. The honey will act as a natural laxative. When he is done soaking, fill his water dish with lukewarm De-Chlorinated water (no honey this time) and place him back in his enclosure in his water dish. Don't feed him tonight. You don't want to make the impaction worse. Keep us posted.