Definitely take her to a vet and get a second opinion. IMO, I'd be a little ticked if my vet decided to drug my dog with Rimadyl instead of trying to figure out that actual problem. Sticking a bandaid over it isn't going to solve it!
If I were you, I'd do a test and see if a few restful days in a row (only enough exercise to keep her sane, and keep it slow) helps. If it does, I'd ease up on the amount of exercise she's getting. How old is she? If she's young (under two years) you don't want to overwork her on a regular basis as you want her to finish growing and maturing before putting too much stress on the joints and bones.
Young dogs are still allowed to run! What you don't want to do is *forced* exercise, especially on pavement. You can still let them run around in a yard or play fetch though.
