Ridge Rough Black

I asked this question before but didnt have much description. But i found a baby turtle with a small tail and green skin. On its skin there are black dots all over it and the shell is rough. It has a tall ridge on its shell and sort of has small points on the side of the shell. It hasnt eaten in about a week. Idk how it is still alive, but he is still swimming around in the aquarium i put him in. He has a pointy nose,i guess that's what it is, or mouth. I live in New Caney,Texas. I found a big turtle prior to finding this one that looked just like him and it was crossing the road and walked into the ditch and just sat in the water because i was trying to get it. Please help me if you can. Thank You