What is going on with my slider turtle?

I have a Rio Grande slider turlte who I have had sine February 26. It was about an inch long when I got it, and is now about three inches. It appears to be shedding yet again, but now is continuously basking and won't eat much. It is usually rwvenous and begging for food when I approach the tank with worms, but it seems disinterested. I read that their shells stay pretty soft for up to a year, but the back edges of its shell seem kind of toothy and the carpace is a little irregularly textured. Could it just be shedding, or is it likely that it is sick? I have a yellow-bellied slider in the same tank who is doing totally fine. They both get aquatic plants, juvenile pellets with a good calcium to phosphorus ratio, and meal worms.