Good advice mrphysio+ I agree

The body is making the muscles spasm to splint or guard an underlying problem in the back this is often down to two things disc bulge or inflamed facet joints (the small joints of the back of the spine which are highly sensitive). As long as you don’t have leg symptoms I would recommend manipulation most of my patients get relief with 24hrs post treatment.
Go and see a Chiropractor or Osteopath or possibly a physio that has been taught this technique post grad. Warning: if you are very tender it might ache afterwards but as the inflammation goes down (24hrs) you will start to feel loads better.

hope that helps