positive test-promethazine

Brittany
I have been lightly bleeding on and off for 12 days... I was frustrated thinking maybe steroid I took last week screwed up my cycle. I mentioned it to a friend and she asked if I could be pregnant, which honestly didn't even occur to me since I'm bleeding!  I'm supposed to start another round of steroids today for a cough/allergy stuff... figured I should test before starting and surprisingly it is positive. 
BUT, I have taken promethazine (phenergen) in the past week. Not a lot--small amounts only before bed, and the last dose I took was three nights ago. I have read it can cause false positives and should be clear from your body in 5 days.  Im unsure whether I should re-test tonight or wait another day.
What would you do?