Anemia of inflammation was my first thought.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6536698/#:~:text=Anemia%20of%20inflammation%20(AI)%2C,%2C%20autoimmune%20diseases%2C%20and%20cancer.
My labs were messed up more than once but not as much as yours are. I was also HLA-B27 positive. Having recurrent uveitis which is also associated with being HLA-B27+ made the diagnosis easier. Unfortunately, a diagnosis didn't make it any less painful. Massive amounts of prednisone helped but now I'm on a biologic.
https://emedicine.medscape.com/article/1201027-overview#:~:text=HLA%2DB27%20is%20associated%20with,cases%20are%20HLA%2DB27%20positive.
My diagnosis was reactive arthritis. The most notable autoimmune disorders that are associated with being HLA-B27+ include: ankylosing spondylitis, reactive arthritis, Behçet's disease, inflammatory bowel disease, and psoriatic arthritis.

I was diagnosed 30 years ago. I don't have disfiguring arthritis but there is extra bone and arthritis on imaging everywhere they look.