What Causes Pain In Lower Back And Leg?

HiI have been having issues recently with bones in my body. Since i was about 12 (now 21), i have noticed bones in my body crack. It started off with just my fingers doing it but now i can list toes, ankles, lower legs, knees, lower back, shoulder, elbow, ears and neck as places where bones are cracking. What makes me worry is that for about 5 weeks now I have had pain in my lower back and left leg. Like a shooting pain (left leg) and general pain in my lower back. To get rid of the pain I have to crack the bone in order for the pain to go away. Yet 10 minuets later it will be back.Any answers to this would be gratefully appriciated Thanks James