OC, tamoxifen, and cysts

I have had fibroids with no symptoms for 14 years.  My periods were so regular that I scheduled my breast surgery around that calendar.  I began tamoxifen four months later and my periods stopped cold with only two or three in a three and a half year period.  Last year in my routine exan for the fibroids, my gyn said she thought they had grown and so my oncologist said to stop taking the tamoxifen.  At the same time they put me on thyroid medicine due to Hashimoto's Disease. (I think I had this for some time and was told repeatedly that it was just menopause - which I did not agree with.)  Six weeks after the stopped Tamoxifen and started Levoxyl I had a month long period which was last December.  Ever since then I have had irregular periods and some heavy bleeding twice which I never had. My estradial in May was under 10 and 141 in August.  This month I had my routine ultrasound for the fibroids and they said that both ovaries had masses on/in them, most likely an endometrioma.
They want to do a hyterectomy to rule out ovarian cancer but I think all of this has something to do with the tamoxifen and thyroid issues.  I seem to be all over the place.  Do yu have any thoughts on this?