What causes constant body pain?

hi my name is Julie and i have constant pain everywhere in my body, this worries me because i am only 16. Most of the time i have pains that last 5 - 20 minutes and go away but sometimes these pains last for hours or all day. Areas of pain: big toe, left lower rib cage (very sharp and intense. on and off) ,knees and ankles (feel in general) and my arms, in my elbows especially. i cant even brush my hair some mornings or work four hours without feeling like i could collapse from the pain. please help