My grandaughter was 9 when she started. We worked hard to teach her to self inject. Despite her special needs it didn’t take long. She was on both Enbrel and MTX at the time. Camp Limber Limbs sponsored by the Arthritis Association made a huge difference. Cool Camp. Anyway check out their resources. They still send out a backpack of goodies for the kids and some great parent materials as well as stuff for the schools.
And especially: https://www.arthritis.org/juvenile-arthritis/get-your-ja-power-pack
I don’t want to sound preachy, but I hope in addition to the hard work you have done with Dermatology, you also involve a pediatric Rheumatologist. ( they are differnt than a egugular ol’ rheumy - much different) Genetics is against you. Your son is at the age where his regular pediatrician will often blow off things as “growing Pains” One of the major themes of the Arthritis Association is empowering parents to say "NO, what my kid is experiencing is not “just growing pains” A pediatric Rheumy will treat very aggressively “growing Pains” (far more than what an Adult rheumy would do) Doing so has incredible results. In fact numbers indicate that aggressive treatment of Possible Arthritic conditions at this age has a high probability of “retraining the immune system” through developmental stages to the point by age 19 or so, adult arthritis just doesn’t happen…