ok so i started cramping on friday (5/28/10) and it seemed like i was spotting so i took some alieve and kept moving. 2 hours later, no bleeding, still cramping and back pains. 2days later, i have like a brown discharged slightly pink but still nothing major. I usually start the last sunday of the month but it still hasn't come.

I have had unprotected sex for the first time last month but i took a (cheap) pregnancy test and it said negative.
Should i take another (better quality) test now that its been a little more time since i've had sex?
And could the late cycle just be frm age?

I've been irregular my whole life until i moved out my moms house in october 2009 and its been like clock work every since then except this time....im a little scared :-(