pregnant?

My period should be due around now (I'm irregular so it happens whenever but usually every 30-40 days) I've been having cramping and feeling like af is coming for over a week now. I had a small amount of brown discharge after I peed 3 or 4 days ago but nothing since and I don't usually have mid cycle spotting. I tested negative this morning but have been having nausea on and off all day. I've also been hit with waves of fatigue the last 2 days :( this isn't your average tiredness either, it literally feels like I'm about to be hit with the flue and then I'm fine. I have no clue what's going on :(