if he is eating the leaves I would offer him some greens and veggies (Kale, squash) Is he pooping OK? Ficus are safe in small amounts, but if he eats excess he can get contatc dermatitis and/or sores in his mouth. Is this plant new? did you repot? wash well to remove any pesticide residue? Sorry, just thinking of any possibilities. Is there something IN the soil he maybe trying to get to? Though I cannot imagine what.
If you are goign to the vet I would bring a fresh poop so a fecal can be done while you're there. Maybe you can talk to the vet on the phone to see if s/he even thinks the visit will help.
hmmmm.....
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Chameleon Help & Resource Info
0.1 Veiled Chameleon - Luna. She's now hanging from her big jungle gym in the sky
1.0 Beardie - Darwin
0.2 felines - Kyndra and Lita
0.1 African Clawed Frog - Skipper
0.1 Mad. Hissers and she is on the loose!
0.1 Chilean Rose Hair Tarantula - Rosa Leigh
0.1 Goliath Bird-Eater Tarantula - Natasha
?.? Pinktoe Tarantula - no name yet