My cat is getting older, and it seems like there are a few problems with her?

So, my cat is getting old. She's probably over 10 years old, I'm not very good with age.She started chewing her back, right where the tail starts. The hair is very short there now.When I rub her back (at that area), she used to stick her butt up, but now she starts licking everywhere and it seems forced.I was rubbing her back and i felt a small lump near her spine.I have also found a cut near her mouth, and underneath her chin.My mother had said she is okay and she eats fine, but I hate to think she is going through pain.We have gone to a vet, but they did practically nothing except give her a ointment which did nothing....it was so expensive, too.Please help!

I myself have a 12 year old cat, its natural when the get older to develop issues like with their urinary track, stomach sensitivity, same kinds of things we experiance as we get older.