Knee pain, followed by muscle pain, lasting days, 15 years old?

A few days ago, Friday I think, I squatted down and my knee exploded w/ pain.
All my life I have dealt with my left knee sometimes occasionally slightly dislocating and popping it back into place. White hot pain. Nearly fainted from it.
But now, EVERY time I squat it does this. And every time I bend my knee it hurts. I popped it weirdly the other day and it stopped hurting so much but it still does.
And now my thigh muscles next to my knee seize up every time I bend my knee much at all, help?

?2015-08-31T12:06:26Z

Go see a doctor. There 's a wide variety of reasons why this might be happening, and if you want it to stop, you'll need to get some tests done. You'll most likely get an x-ray done and if that doesn't show anything, maybe a CT or MRI. If your muscles are hurting now too, that's probably a sign that something is wrong.