Desvenlafaxine prescribed by Rheumatologist for severe spinal pain

Hi, my first post here. I have both Osteoarthritis and DISH in my spine. I have facet joint degeneration ranging from mild to severe, mostly in my cervical spine, a bit at the top of my thoracic spine and a bit in my lumbar spine. The DISH has caused several areas of fused vertebrae in my thoracic spine, which means it must have been there for some time but was only diagnosed about 8 months ago. The facet joint degeneration in my neck causes an ache at times but no other symptoms. I would have some occasional pain and inflammation, mostly after activities like gardening, and it always responded well to Ibuprofen. About 3 months ago I developed severe pain in the centre of the small of my back, a deep burning ache. It doesn't respond to NSAIDs, Paracetamol, or even Endone. A heat pack provides relief. I have no pain in bed regardless of laying on my back or on my side. Bending and movement don't make it worse. Any nasty pathology has been ruled out. I've had an assessment at a centre for Neurosurgery, no trapped nerves, etc. They've said I'm a bit of a mystery and are presenting my case to a multi-disciplinary team of specialists.
My Rheumatologist has prescribed Desvenlafaxine, an SNRI antidepressant, for pain. This is commonly used in lower amounts for pain management. I'm not depressed, however I need relief from this pain and although I strongly don't want to take Desvenlafaxine, I am considering doing so.
I'm interested if anyone has taken Desvenlafaxine for similar pain as mine, did it work and to what extent, and did you experience side effects? Also, if you have stopped using this medication, did you have any issues when tapering off of it?
Thank you for your time.