My right ankle is swollen but not my left. pain in my right inside knee and upper groin area. what could it be? i exercise daily, dont smoke nor drink?

The exercising could have caused a strain in that area. The muscles and joints in area could be inflammatory from trauma of exercising or a fall. You can try hot compresses but if this condition continues see a orthopedist for x-rays or an MRI.

Ankle swelling in one extremity on such a young person concerns me. I would have this examined as soon as possible.