....when my daughter was about your age, she sustained an injury at work. She got a very hard hit to her shinbone on one leg. It got really bruised. But, no big deal, right? A few months later she developed lumps on that leg, close to the shin bone. They kept getting bigger, very scary! We took her for x-rays. The doc could see these in the soft-tissue, but did not think they were cancerous, which was our first thought. Then she was sent to another doc who did an MRI. Turned out to be some kind of reaction by the body to that injury. She was treated with an NSAID for about 6 weeks and it resolved. Thank goodness! Injuries to the joints can set up a trype of arthritic process and should be evaluated as soon as possible. Because, left untreated, it can lead to deterioration. I know, I have had tons of problems with my shoulders from dislocations. And may have to have one replaced. Not a pleasant thought I have had one neck fusion and may have to have another. I believe that it has been an arthritic process set up by a neck injury when I was a teen. My advice to young people: treat your body with respect!!!!! Everything you do now will effect your health for years to come should you be fortunate enough to live a long life. OK, done ranting.