My Periods Are Always Normal And On Time. This Month

My periods are always normal and on time. This month I didnt have a real period.. I spotted and I have been for 2 weeks now. My stomach has been hurting non stop. I took a pregnancy test a week ago and it came back negative. I dont know what could be wrong. I have stuff coming out of my nipples if i squeeze them. I had a baby almost a year ago as well.