For almost half a year, my anus has been itching terribly.

For almost half a year, my anus has been itching terribly, mainly in the evening and at night, as well as in the morning. I have already been to a gynecologist, a dermatologist, as well as an internist. The dermatologist did not find hemorrhoids, I got various antifungal ointments, for hemorrhoids, antiallergic and completely nothing works ... I performed a calium test for the presence of parasites and three times the result came out negative... I don't know how I can deal with it anymore, recently the doctor told me that "she doesn't know what it could be"