My right knee keeps swelling and it grinds when i bend it and very painful what could be going on?

Arthritis, advanced: These symptoms are most consistent with moderately advanced arthritis. You need to have an orthopedic evaluation and X-rays in the near future. If you are overweight, you should also consider a weight loss program. For now you may take an anti-inflammatory medication for the pain and swelling, assuming there is no history of gastric ulcers or bleeding from the colon.