I've had hip pain since i was 18 when a car had fell and broke it in 4 places and i've had mris cat scans xrays and bone density tests done and all the drs i went to say nothing wrong what could be wrong with my hip?

Variable : Tough to say without looking at you and your studies. What are your symptoms other than pain? What kind of pain is it? When is it? Have you seen an ortho doc?

Hip pain: Its not that 'nothing is wrong'. Its they can't see/find a specific problem to fix. You have a lot of scar tissue and bone remodelling. You don't say if this is joint pain on movement or not but I would surmise the joint is an issue. Try a steroid injection into the hip joint. It does have some risk of other problems. The pain is most likely scar tissue. Perhaps remove the hardware. Ask ortho.