Nausea and awfulness :(

Lex
So I have pcos and haven't had a period since last July. Well this month I was complaining of my breast hurting really bad and I had bad nausea so I think I'm pregnant! But then all of a sudden I start AF. So then half way through that I get horrible nausea in the morning and late at night and I have to wake up during the night to go to the bathroom which I've never had to do before. My breast still hurt. I had a pregnancy test during day 3 of period because I was hurting so bad from the period I had to go to the hospital and it was negative  
Can someone help me out? I don't understand what's going on!