Are my mood swings due purely to menapause or are they related to having been on Effexor?

I had breast cancer surgery 2 years ago.  I was taken off of estrogen, & put on Tamoxifen & Effexor.  Because of a mix-up between doctor & mail-in pharmacy I was without Effexor for 2 days.  In those 2 days I was nearly out of control, bouncing between rage & tears.  As a result I told my doc that I wanted off the drug.  It's been 3 weeks now since I was weaned off of it.  Now I have full blown menopausal symptoms, hot flashes, chills, anger & sudden weepiness.  The moods are a lesser version of the 2 days unintentionally without Effexor.  My question is this:  Are my current symptoms purely from menopause or do they have anything to do with having been on Effexor?