It is possible that your symptoms are from an interaction with some other drug or supplement you may be taking. For example, ivermectin, according to cautions posted by FLCCC, interacts with quercetin. You might want to also avoid taking any other supplements, such as citrus bioflavonoids (which probably contain quercetin) or some multi-vitamins (some contain quercetin), and any meds you are taking; for example, maybe wait at least two hours after taking those before you take the ivermectin. And likewise, wait one or more hours after taking ivermectin before you take your meds or other supplements (for example, any herbal blends that often contain 1 or 2 dozen ingredients – and only God knows what interactions their combinations might cause).
Good luck!