back pain is usually caused by the vertebrae..you might have narrowing in between a few vertebrae, causing pressure on nerves.. see an orthopedic

It can be related to MS, but please see a specialist as soon as you can, my back pain has been put down to MS for years, I just accepted it at first but then I recognised it wasnt the MS and I got reffered to Muscoskeletal via my doctors. I recently had an MRI scan which revealed inflammation and bony spurs in the thoracic spine, they are now saying I have Axiel spondyloarthritis, I have chronic thoracic back pain, like a deep aching, popping/cracking nosies and it feels worse when im at rest, particularly in the mornings and at night. So im now waiting for Rhumatology to see me.

You need to get with a spine specialist and have them check it out. Not all pain comes from multiple sclerosis

Probably not, Wildone78; read Jj's answer which is one cause. Others are from poor posture, fused bones, slipped, bulging or ruptured discs in the spine, scoliosis and other back disorders. Get checked out by a chiropractor and see what could be causing it.

Whatever ever you do you need if you can to strengthen your back but gently your whole body comes into it blessings 🌸💐💐💐💐💐💐💐🌺🌺🌺