dislocated knee?

somethings happened with my knee, twice now. it does something and it puts it into huge pain, the first time i couldnt move it without being alot of pain, ended up going to the hospital. the doctor said its fine which i dont believe, the second time i straightened it quickly and it went sort of ok. i started running alot lately, its never happened before and not during running, ive never had any knee pain whilst running before. Any runners(or anyone) experianced something similar? i dont know if its tendons/ligaments or if my knee is dislocating.

It may be that you have dislocated the patella (knee cap), which usually happens when the patella goes "off track" to the outside, and pops back into place when the knee is straightened out. Many times by the time the ER doctor sees it, it is reduced (back in place). Sometimes it can go "almost" out, and still pop back. This is less injury. The main problem with patellar dislocation is the tissue damage on the medial (inner) side of the patella. This can heal loosely, and make the patella vulnerable to recurrent dislocation (instability). The treatment is immobilization in extension for a couple of weeks then slowly allowing the knee to flex over a few more weeks. You might get away without doing this, but since you've done it twice, I worry that it will be a big problem going forward.

You should see a doctor. In the meantime, do lots of leg lifts (isometrics) with the knee straight to minimize atrophy.