What Causes Constant Vaginal Discharge While On Depot Shot?

I have been on depo for 2 years now and have never had any problems except for the normal weight gain. In february I was on clarithromycin and I had sex on one of the nights I was on it. Anyways I've been feeling fine until now. I was sick a few days ago- lots of diarrhea and a lil vomit and I was weak and all but now im getting better. What's worried me is the past week or so I've been having an almost constant white discharge. And today when I used the bathroom I wiped n there was blood and white discharge on the tissue. What does this mean. Am I pregnant. Im worried.