She is a Cooter, although the care is the same as Sliders.
There would appear to be previous damage to the shell, but I would be concerned at the redness showing. We are currently treating one for shell rot and it is taking a long time. There is probably "something" underneath those scutes and really (depending upon your knowledge, confidence etc) needs a vet to remove the infected areas and treating. This involves dry docking. It also appears to be green in places?
The top of the shell looks ok, but a bit of sunshine wouldn't go amiss! What sort of temperature is the basking area, and what do you feed.
This is purely my opinion, others may not agree - hopefully someone else will be able to help also.