HELP!!

So, yesterday towards the end of the day, around 7pm, my lower stomach and head started hurting. I was in pain but it wasn't that bad. When I went home, it still hurt so I took an Advil to see if it will help. It did until now, as I'm writing this, at 4am, both of my stomach and head started to hurt again. This time I feel nauseous and can't seem to fall asleep...My period is supposed to come in 4 days and last time I had sex was either on the 13th or 14th of Sept...I will get a pregnancy test when I "wake up" if i even go to bed... what do you think? Am I pregnant??