Hello Fluffy! Tiny could very well be shedding. Spring disease symptoms includes lethargy and skin discoloration. We can rule out lethargy because frog is active and eating. Has it drastically changed skin color lately?

Here is link to their care sheet, please take a look and do corrections to frog care/enclosure as needed: Frog Forum - White's Tree Frog Care - Litoria caerulea. Good luck !