am I pregnant

Two weeks ago i took two pregnancy tests they both came back negative, two days later I got "my period" I put quotation marks on period because my normal period is heavy for 5 day and I get really painful cramps. but this one was really weird because the first day was really light so light I was using a panty liner, second and thrid day was medium/light, and the fourth day it was over. Before I got my "period" I was having really bad back pains and I was really emotional. After I was still having back pains,getting light cramps, and I always feel tried. so two days ago I got another more pregnancy tests and again negative. today I started getting headaches and my nipples hurt. I no idea what's going and I don't know what to do. am I pregnant or is something else. PLEASE HELP ME😣😣😣😣😣😣