Help with my turtle please

I need advice

Got this little dude from my sister. As the pic says his tank was cold and dirty. I took little guy home and I've got him in a small tank for now. He's got a basking rock and uva-uvb light. Heated water and I'm planning on getting a filter asap. I have a 60 I can eventually move him to but he's incredibly weak right now. She says this little guy is 3 years old so very obviously stunted.

I cleaned his shell and noticed a bunch of stuck scutes. Kinda poked at one gently and it's flesh underneath. Not new scute. His shell is soft and I've literally never dealt with a soft turtle. He's definitely not supposed to be soft.

He's also still refusing to eat. Was completely limp when I first picked him up out of his old tank. Floppy head and feet and wouldn't even open his eyes.

I've had him for about 24 hours now and hes finally warm and moving around a little I've offered blood worms, small mealworms, and pellets and he won't touch any of it.

My questions. What do I do about his soft shell? And will it just take more time for him to be interested in food? Will he catch up growth wise?