Sorry for your pain. Back pain is invisible to others, and therefore often does not get the the medical attention that is needed. I am not a doctor. I have suffered with back problems for 20 years, (Now 58). I was an x-ray technician, even with this background I could not get the tests I needed.
If a disc is protruding into the spinal column, stenosis has set in, pathological fractures from osteoporosis, and many other causes have come into play, it is possible that the nerve path followed back to the spine will indicate the level in your back where the source of your problem lies.
Ask your doctor about Celebrex, hydromorphone, or Cyclobenzaprine HCL. These I found addressed the muscular pain much better than Tylenol. Tylenol is very brain'numbing'. Again I am not a doctor. Best of luck.