Cause of (chronic) joint pain in 17 year old?

I'm almost 17 and have been having bad joint pain in both knees, hips and ankles for as long as I can remember. When I was young my doctor diagnosed them as growing pains, however they never went away. Over the past 5 months I have been in pain for hours almost every single day and NSAIDs are not helping. 2 weeks ago my mom took me to the doctor and he ordered a CBC, RF, CMP and ESR blood tests. They all came back normal so the doctor does not know what is causing this joint pain. He said I could go see some kind of joint specialist, however I don't think my mom will take me. Does anyone know what could possibly be causing this? Please help!