Is it possible that the ivermectin dose was not strong enough? Or perhaps not used for a long enough time period. I work in hospital and was reading how they treated skin mites (scabies) infection, with ivermectin 200mcg/kg on days 1,2,8,9,and 15. They also are using permethrin topical 5% from HEAD TO SOLES OF FEET (deratologist literally wrote that in order) for 7 days. Hospital protocol for this is room sterilization and all caregivers that had contact with patient before diagnosis have to be checked and treated as well. Sounds like your mite is most likely the Demodex mite, but it is treated the same way once it has colonized.
You are not crazy. It is a real thing. I don't know why parasites are so misdiagnosed. I feel certain that they are much more prevalent than most realize. Don not give up on the ivermectin; it needs to be taken 1-2 1st week, 1 to 2 doses 2nd week, and 1 dose third week at minimum. This is the oral dose I'm referring to; it goes for injectable as well if you go that route(not FDA approved in humans, but I can speak from experience it can be done). Hope this helps.