YES!! I would try a smaller plastic tupperware container that is more his size. Do up a paper towel in the bottom, some branches, and some fake leaves for him to lick water off of. Also if you leave him in it, hook up the UVB bulb a sufficient distance from the cham!
I think this was part of my problem with my little 10wk panther(now she is close to 4 mo). It seemed like she wasn't growing for the LONGEST time, but I think she must have been having a hard time hunting in the space that was most likely too large for her.
Is your panther showing any other signs of being un-well, or just not eating.