You've got to see an orthopedic surgeon who treats lots of athletes--especially gymnasts (I'm assuming, here, from your talk of a tumbling pass). There's a great doctor who takes care of the US Olympic team in Alabama....
Anyway, PT's are very useful, and most athletes couldn't get by without their trainers....but they cannot definitively diagnose your knee injury. For that you have to see a knee specialist orthopedic surgeon--fast.
In the meantime, if it were my knee I would be on crutches with a brace on. PT's should have access to it. Or at the very least an Ace bandage to help reduce swelling. RICE it like crazy. If my knee felt that wobbly and unstable, I wouldn't be bearing my full weight on it. I wouldn't be walking without crutches to take some weight off the injured joint. It could be a sprain, but no one can say unless they are a specially trained medical professional with access to diagnostic testing services.
Just my two cents' worth.
Heather