Question about Ovarian Cyst

I am a 3 year Breast Cancer survivor.  Because I take Tamoxifen, I go for an annual pelvic ultrasound to check my uterus and endometrium, which has always come out fine.  Last week, I went and there was a 4 cm circle on my right ovary.  The Nurse Prac said it was a huge egg, then she said it was too big to be an egg, so she ordered a CA 125, which came back at 33.  She said because the mass showed up to be perfectly black, that that was a good sign it was fluid filled.  It was exactly 14 days from the first day of my last period, which would have been the "perfect" time to be ovulating.  My question is, is 33 too close to abnormal?  Can an egg follicle be this big and be benigh?  Since being on the Tamoxifen, I have terrible cramping when I ovulate, which the nurse said is normal.  I'm trying to stay relaxed, but I have made an appointment for a second opinion with an OB/Gyn.  I would appreciate any information.

[mariaclau]

My doctor told me I have a cyst in my ovario. I'm 37 year old and trying to get pregnat. The cyst would be a problem?
Thank you