i started what i thought was my period almost 2 weeks early

Okay so my b/f and i have always had unprotected sex, (2 years+), and i am on b/c i take it the same time every day, and i have not missed one once this month. but today i started what i thought was my period almost 2 weeks early, but its a watery very very light blood. i have mild to severe stomach pains, near my belly button, so its not cramps. I have nausea and a headache as well. I have taken advil, but it only relieves my headache, and only for a short while. My stomach is bloated, but its the normal uncomfy cant wear jeans bloated, its very hard, it feels almost as if im flexing.
I dont know what to think. Please help.