I have pain in the back of my hip in my si when i lay on my back it pops which hurts and when i turn my leg or move it tightens and strains down myleg?

Get Specialized P.T.: It sounds like you may have si joint instability. A physical therapist with "special interest and training in si joint therapy" would be best. Actually call around and ask if they have a therapist with "..." if you need a referral from a physician, mention the name of the therapist you located. Make sure you are taught at-home-exercises to stabilize your si joints. Max 3 months or change therapist.

See prior answer: Spondyloarthropathy is possible at your age, but it will require your doctor's examination to clarify this.