Just a thought, since you have horses. You may be getting reinfected through manure or those tiny eggs laid on their skin. I no longer have horses, but when I did, I followed the rotation schedule. They were wormed 4x a year, each time using a different type, pyrantel, ivermectin, bendezole, praziquantal. Maybe deworming yourself and often is going to be needed for you as well, especially with a weakened immune system. I saw someone on here used horse wormer on themselves, I have actually been considering that.