test came back negative...

got tested a few weeks ago for STDs during an appt with my gyno because my SO and i have unprotected sex and figured it wouldn't hurt to know. test came back negative and he and i hadn't seen each other since before i had the test taken up until yesterday (i.e., no sex) and i know he's not cheating or anything, but i woke up this morning with small itchy bumps near the opening of my vagina. i got a new razor and tried it out this weekend when shaving, so is it possible that these bumps are just razor burn?