Constantly have lower back, hip and tailbone pain I also have constant pain in my arms and legs what could this be its been ongoing for 3 years now?

Rheum Eval. What you are describing is somewhat concerning for what we call connective tissue disorder. Would recommend you see your doctor for an initial evaluation and x rays/blood work. If no answers, recommend evaluation by a Rheumatologist. Hope this helps. Best of luck with this. Dr R.