the best advise I can give you is to go to your local clinic, they will run x-rays to see what is wrong with your knee. They should be able to tell you some exercises that you can perform with out pain, and if its serious they can take action before it gets worse. I went last week because my foot was bothering me and they ran x-rays, it turns out I had broken it. So I would say going to your clinic would be a good idea, just in case. Hope that helps :)