Welcome to Gaia! ::

My first thought is arthritis but I'm not a doctor. My sister had a torn meniscus that caused her pain.
If you want to try something, I'd try glucosamine with conjointin. It's over the counter but I'd still talk to your parents before taking it.
I can never remember when to use heat or ice but one or both might help.

Now speaking from experience, you are going to have to be pushy with doctors. My sister suffered since she was in grade school and had an MRI done in high school. Our mother finally had it and really pushed the doctor for an MRI or something. And thus, the problem was revealed.

I need spinal x-rays because of an old fracture but my doctor is telling me to do physical therapy >.< *eye roll*
Be pushy if it is really concerning you. You can't cure what you don't know.