What Causes Hot Flashes, Night Sweats And Fatigue?

I am almost 56 years old. I have been on birth control pills until this past December. I went off of them to see if it was masking metapause. I had one period. Now I have missed (or am late)…..I have hot flashes, night sweats….some fatigue. But I also feel somewhat nauseaus. I am confused as to it being menapause, or the rare chance (have always used another form of birth control - not once had unprotected sex ) that it is pregnancy. When I read symptoms of menopause, only a few mention upset stomach. Any thoughts?