OK, When I was in school many years ago ! I was always doing some kind of sport, played Football and was approached by Bristol to sign forms, also play Rugby and our team won the school boys cup unbeaten all season and was ask to go train with Newport Rugby. After leaving school I kept up playing and even took up badminton, and later took up Tae kwondo well before Bruce Lee was even heard of, won the first every Welsh championship in Barry . It was then I was getting pain in mt lower back, I had pain there for years but always work past it.
This time I was told by specialist at the UHW that I had Ankylosing spondylitisi
http://www.nass.co.uk/ , In time it went all over my joints and still have great pain now Im a lot older. I had an op last year and had a complete knee replacemnet, one thing I would say to you is 1st you MUST ask your Doc to be refered to a rheumatologist THIS IS A MUST!!!
Now they may offer you anti inflammatory, TAKE CARE! cos long term they can give you kidney problems.
Then you have cortisone injection, again not a good thing and only very short term treatment, they shouldnt be taken all the time. Athritis can come in many forms and all very painful, But the very first thing to do is get to your GP and dont ask, TELL HIM! that you want to see a Rheumatologist. It maybe that its not Athritis ,but it could be a cyst in your knee, its pretty common. Also there are foods you can try that are Anti Inflammatory foods, here is a link
http://nutrition.about.com/od/dietsform ... amfood.htm BUT! dont think you can eat them and it will go straight away, it takes a long time for them to get into your system and help IF IN FACT THEY DO HELP ! I say that cos some people it may work for other may not. Good luck and I hope some of this may help you. BUT YOU MUST MUST MUST go to your GP and demand to see a Rheumatologist that is if it really is Arthritis you have.