When biologics fail what is next?

My son was diagnosed with ankylosing spondylitis at age 19. His symptoms are very similar to RH. He was initially given NSAIDs, steroid injections, sulfasalazine's, then onto TNF inhibitors. Enbrel did well for awhile. Once Enbrel stopped working, he tried several other TNFs that failed him. He then moved onto the IL-17 inhibitor Cosentyx, which caused "reactivated viruses" and made him very ill for 6 months. He is now 24 and can barley move from so much pain. His life has been put on hold with college and a social life. This disease is progressing and the pain from it is becoming unbearable for him to handle. A once active athletic young adult now barley able to move. Very hard to watch as mother.

I have Lyme disease and I take a mixture of herbs and pharmaceuticals. The herbs work very well for me. My son is pro pharmaceutical and doesn't seem to believe that herbs will help him. So my big question is...Has anyone tried Devil’s claw (Harpagophytum procumbens)? This herb is widely used in Europe for treatment of arthritis pain, headache and low back pain. A number of scientific studies have found that it can help relieve the pain and stiffness, particularly when it affects the knee or hip. Also, boswellia serrata (Indian frankincens)? The arthritis foundation claims that it reduces inflammation and treats RA, AS and bursitis. So where to go after biologics fail? Please, any advice would be greatly appreciated!!