Well, without a clinical evaluation it would be difficult to comment specifically on the situation. The symptoms could be due to complications from a previous injury or could occur due to an unrelated episode. Possibilities that may need to be considered include fractures, loose bodies, inflammation, injuries to tendons/ ligaments, growths/ masses etc. I would suggest getting this evaluated by a primary care physician or an orthopedician for an accurate diagnosis and appropriate management.
Hope this is helpful.