I'm 15 and been doing marching band for past 4 weeks 16 hours every single day.so I wake up perfectly fine and practice for 4 hours just fine but then we left to go to the show. Do I sat on the bus for 45 mini it's. sitting on the bus and my knee was perfectly fine the whole day and for practice but then I got on the bus but when I got off the bus ,it was swollen and has been for two days, I've been whereing a knee brace but it still won't let me move it past a 90 degrees , so do I have arthritis?