Am I Over thinking This?

Recently I was on vacation from college and I visited my family. During the visit my family took a small (and very regrettable) road trip. Due to poor choices and planning on the way back there was an additional person in our car and as a result I ended up riding in the back with our luggage because I'm the smallest. Every since then I noticed bruises on my legs (they eventually went away) and severe pain especially in my right knee. It took weeks for my mother to take me to the hospital because she kept compairing my pain to her's because she has arthritis. At the urgent care I showed the doctor how my leg is now bowing like the Nike symbol and my Mom kept adding in her own medical problems. She never told the doctor about me being folded up in the back of the truck with our luggage so the doctor said it could be arthritis however after seeing my knee the doctor thinks my knee could be giving out on me now in a combination to arthritis(thanks to the opinions of my mother) I want to go get a second opinion (on my own) and actual xrays of my knee. But could I be over thinking this; the doctor did give me a brace to stabilize my knee temporarily but I'll be walking around campus soon and I don't want my knee to give out especially if it can be avoided.