Spinal lesions and fractures

Has anyone heard of an autoimmune condition that leads to lytic lesions on the spine? Around 2021-22 I developed unexplained symptoms: joint pain in feet and wrists, and then vasculitis in lower legs. Rheumatologists did blood work and x-rays and said it's inflammatory arthritis, but no rheumatoid marker. Then this year I developed a compression fracture in my lumbar spine, which led to posterior fusion surgery. The cause was a lytic lesion in my lumbar spine, and I have smaller lytic lesions on my thoracic spine. All doctors assumed multiple myeloma because I have MGUS, but PET scans, bone marrow biopsies, bloodwork, and urine analysis are not showing multiple myeloma. Doctors don't know what to make of it. Last rheumatologist says nothing she treats would have caused a compression fracture in my spine. I'm not sure where to turn next, and I'm worried about the lesions on my spine progressing to something more serious. I am an otherwise healthy 60-year-old woman who was very active until all of this occurred.