I too tried Hurmira - I am not sure if you can build anti-bodies to Hurmira but I did to Remicade (a blood test confirmed this, I still had anti-bodies against Remicade 10 years Later) and had trouble with any other anti-TNF Blockers including Hurmira. I started feeling ok with the first couple doses then got progressively worse with each additional dose.
If it makes hime feels worse I think he should stop, and try something else.
I had trouble with Enytvio as well. I hope you son has better luck. I am using Stelara - No side effects for me and helps some.
I hope your son feels better soon,
Carolyn