A baby RES that I got about three months ago is having trouble eating. I just noticed this, but it might have been going on since I got it (he's in a tank with two other turtles, and I didn't notice that he was having trouble eating until recently). He's very small (shell length barely 3/4"), and hasn't seemed to have grown at all since I got him. I feed baby Reptomin pellets, and while he bites at it and is usually able to get it in his mouth, he usually can't swallow it and ends up spitting most of it out. I've tried breaking the pellets in half, but even then they seem to big. On occasion, I feed a mealworm, but he has difficulty eating it even if I break it into about five parts, each maybe 1/8" long. He isn't exhibiting any unusual behavior other than this. His shell is a bit soft overall, but many of the other baby turtles that I've had also had soft shells in the beginning.
In terms of raising conditions, I had kept him in a ten gallon tank with two other baby/juvenile turtles until I noticed that he wasn't able to compete with them for food. I've just switched him over to a smaller, three gallon tank that has one other baby turtle in it. The water temperature is kept at around 80 degrees, and I have both a basking area and a UVB bulb that's switched on for about 8-10 hours a day. Anyone know what's going on, and how I can feed him? I was wondering if it was failure to thrive - I'm new to raising turtles, and would really appreciate the help!
I've attached a picture here, if that helps. Thanks!

