Strange Frog Behavior

[LizardMama]

So I separated Inconnu, my Gray Tree Frog that prefers to stay light gray instead of the dark gray that Poco, my other male Gray Tree Frog, prefers to stay, and put him in a different tank because he was looking a bit scrappy. This frog is strange. I've seen him eat, he'll get nice and round then a few days later he'll be worrisome thin then after that he'll get round again. My other frogs don't do this, I've seen them go to the bathroom, I've seen them eat and they stay nice and healthy fat. Anyone else have this happen with their Gray Tree Frogs?

I make sure to throw in 12-15 crickets 1 night (that's enough for 2 nights) then when 2 days pass give them their next 12-15 crickets, I dust their food and their food is gut loaded before feeding and dusting, I even feed the crickets the dust to be sure that the frogs get the dust in them.