38y female seroneg ra. Plaquenil (hydroxychloroquine) not work. Bone scan show si joints & feet. Start 10mg mtx. Doc said may not be RA since si joints? 4 relative w/ra.?

Talk to your doctor. There are other forms of inflammatory arthritis, which include the seronegative spondyloarthropathies. It might be something like ankylosing spondylitis. Additional testing might be necessary, and a rheumatology referral may be necessary. Also keep in mind being seronegative does not mean you absolutely don't have rheumatoid arthritis.
Other arthritis. Sacrioiliac activity on bone scan and in the feet can be associated with other types of arthritis including reactive arthritis, ankylosing spondylitis, and arthritis associated with bowel disease such as crohns disease and ulcerative colitis. Should as your physician. Other blood tests and sometimes imaging are necessary. There are other medications available for autoimmune types of arthritis.