What Does Severe Pain In The Joints Indicate?

Hi, My name is Tim. I am almost 62 years. I m getting sharp burning pains in some joints or tendons. Sometimes in my heel where the achiles tendon attaches to the heel. Then it might be in a joint. Now it happens to be in my right knee on the right side of that knee just to the right of the knee cap. When I bend the knee beyond 90 degrees to put on socks or take them off but not if I were to do something like a deep knee bend. I teach snow skiing on weekends and putting on and taking off my ski boots both days proved painful too. No problem skiing at a high level though. This is puzzling as this sharp burning almost feels like a tendon or small muscle actually tearing apart when in the certain position and just as quickly it s gone when I change the position. I first felt it a few years ago in my heel, then last year on the back of my right hand and now my knee. Any suggestions as to what might be causing it? I m a vegetarian who eats some fish for approx 20 years now. Wondering if its diet related?