I dislocated my kneecap and I'm taking part on a relay in school next week. HELP!?

This morning, I was just standing and when I turned to look behind me, my kneecap went to the side and I fell down. I moved it back to it's right place, then I had a little black out. I got dizzy and extremely thirsty. It happened last year as well, the doctors said I was fine and I don't think they believed me when I told them my kneecap moved to the side. Anyway, I really need to practice for a relay next week but my kneecap still hurts. It only happened this morning, but I really want it to heal fast! It's nothing serious (well, I think it's nothing serious). Please don't tell me to back out. I really don't want to. The relay is really important to me. Please help.