ENT problems and endo

I have a history of over 30 years of getting flu like symptoms and ENT problems every time I had a period and at ovulation. I never had these problems whilst on the pill or on Zoladex.

Last year I was finally diagnosed with endometriosis and had a hysterectomy and large amounts of endo tissue removed from various parts of my abdomen. However, I am still on HRT and still getting ENT problems.

I had increased sinus pain over the last few days. When I got up Sunday morning and blew my nose, there was a little bit of blood. There was a lot more Monday morning and more again today.

Could this be evidence of endometrial tissue that has got into my sinuses and can it be tested in any way?

(I've tried to get in touch with my GP, to no avail.)