I have no experience with tree frogs but I hope somebody that does comes along. Trust your frog though if he doesn't like the coco fiber (I find mine has a strong scent?) then you should start by taking it away. I had a mouse once and it didn't like wood chips, it turns out the oil was causing seizures or spasms or something.
A lot of people on this site will warn you about impaction and tell you that your frog could eat the moss and it could get stuck in it's tummy.
I don't know what to do when that happens, but try looking into it?
My favorite thing to do when my frog needs to perk up is give him a half hour honey bath. Two spoons of honey in two cups of water, but your frog is tiny? So maybe it wouldn't need two whole cups. The honey perks up my froggy and brings his color back when he's looking faded.
Good luck. I hope everything turns out okay!