I have been on the depo shot for about two years now and mostly never have problems. I usually start spotting like a week before I m due and the blood is like brown and thick not like normal period blood. I got my shot in the middle of April and I m not due again till July 3rd. Well I recently started spotting and it s been bright red blood which I ve never had happen before. I was on a ten day course of antibiotics about two weeks ago for pneumonia which I know lessens the effects of birth control and I ve been sexually active is there a chance the bleeding is from pregnancy? I ve also been on antibiotics plenty of times before while on the depo and never have had bright red bleeding before