After dancing, my left knee hurts as if i smacked it against something. i know i didn't, but it feels like i hit it on wood.

A few thoughts: After looking at your history which includes left hand pain, 'plantar fasciitis,' abdominal pain, carpal tunnel, & pain severe enough to warrant the use of Vicodin, I'm seeing a pattern consistent with disorders from connective tissue diseases (auto-immune) to easily inflamed nerves. A good history & physical incl. hands-on osteopathic exam & other testing may provide clues to an overall cause.

Need exam: The knee has ligaments, tendons, meniscus, cartilage and muscle involved in its actions. You could have injured any one of these. If you have residual pain. Swelling, tenderness, or problems with stairs, exercise or walking you need to be examined by your primary M.D. or an orthopedic surgeon. Your problem could be minor or important.