So normally I start my period around the 20th and 21st of every month, this month I did not start until the day after Christmas the 26th. Then the next day while changing the tampon I noticed that I wasn't really on it anymore. it was just a brownish discharge. My periods normally last about 5 or 6 days. so this comes as a concern to me, because my boyfriend and I have been very sexually active recently and im on the pill but that's the only protection we use. Ive also noticed lately that Im extremely irritable, tired and fatigued. I don't know what it could be please help me figure out if im ok or if I need to go see a doctor.