I have a female RES that I purchased 18 years ago when she was very small. I've never had any serious medical issues with her. Over the past 3-4 days, she's lost her appetite and isn't as active as she usually is. I also noticed she isn't moving her back legs very much. She'll stand on them in the water. She doesn't use them to propel herself around the tank. Her legs look fine and aren't swollen. There's no signs of injury.
She's in a tank on her own. The water temp was a little too warm, maybe 83-85, so I bumped this down a few degrees to 78. I did a half-tank water change tonight which perked her up.
Can anyone offer some information on what may be causing the problem with her rear legs? I also need some advise on bringing her appetite back.
Thanks!

