Hope someone can help

i am 24 and always suffered with pain in my right knee, it always was worse when it was cold and damp and eased in summer. I put it down to a bit of arthritis but never worried about it.

A couple of moths ago I started going to gym and after 2 weeks my left knee started getting painful. I put up with this for a few more weeks and then went to my gp. He told me I had a displaced knee and wanrd me that the treadmill and rower may aggrevate it. So I avoided these. He told me that needed to strengthen my tendons up and said swimming would help.

I have been going swimming 3- 4 times a week for the last 3 weeks and still there is no relief.

Somone please advise as I can't even lower myself up and down from a chair or the toilet. It is really getting me down now, I have tried pain killers and anti-inflammatories but with no respite