Hydrochloroquine also treats and kills malaria and other parasites. I am not convinced your body attacks itself but maybe it is attacking an invader (parasite?) that has not yet been identified. One of the doctors in BC outright told me that I had something but he just could not identify what bug.
I am maybe a bit mean, but it seems like a rheumatologist is a doctor who is not sure what you have, nor how you got it, nor what specifically is causing your symptoms nor how to cure it, but he’ll make an guess. I think a lot of medicine is kinda like that.