listless/lethargic rat

Question
I've got a female rat whose owner could no longer care for her. She came with something wrong with her eye that cleared up with eye ointment. She didn't know if it was an injury or a tooth problem. I have seen no tooth problems. The eye did bulge again where you could see the inner lid but it cleared in a day with ointment. That's the background. Shelby is normally very active and has even leapt from the cage to my shoulder for attention. She's normally hard to examine because she's a mover. Today she is walking very slowly, eating from the bowl instead of taking food away with her and she seems to have some weakness in her front paws/legs. I notice that the paws will curl when she stops walking. She is very submissive with her cage mates -- also unusual. She also shivers when I hold her...again not normal.

Answer
 It could be many things; unfortunately I can't tell you exactly what is wrong as I am not a vet and can't examine her myself.  If she is older (2+) it may just be her slowing down and her body degrading or it could be a tumor, bodily injury, liver / kidney disease or other organ failure, heart disease, bacterial infection, or even a virus.  It may or may not be related to the problem with her eye.  It does sound like it is serious and I would recommend you take her to a vet for an exam.  The vet will be able to tell you what the problem may be and discuss possible outcomes.  I hope she gets better soon, please let me know how things turn out!