What Causes Chronic Pain All Over The Body?

I am experiencing chronic pain all over my body. I have a left knee that is totaled and I am in the process of getting a brace to pull it back in place. It is from a 35 yr old surgery from a broken tibia that resulted in total knee complications. That appears to be causing extreme lower back pain because my leg is so twisted. And I recently had a spinal fusion of L4_5 as suggested by my spinal surgeon. Now the pain is lower in the last disc and severe around the S-I joint. I have been living with this numbness, tingling, pins, needles and very painful condition for the last year following surgery and it is getting worse daily. I have appts. with both an orthopedic (knee) dr and one back at the spine clinic in Durango Colorado. My question is could these conditions be causing this amount of sever pain throughout my body or is there another possible cause. Stress over this isn t helping either. Help!!