Dislocated knee cap, need help!?

I dislocated my knee cap playing soccer, and it slid back into place when the onsite trainers straightened my leg. I went to the doctor and they are having me get an MRI just to make sure that there is no muscle tearing (acl, or meniscus). I have a splint that I wear when I leave the house, and I do not wear it at home. My knee feels really weak, is that because of the dislocation or could I have actually torn something??