Im on birth control, and had a normal period last month March 26th. I ended up having to go out of town the very next day, While out of town I had a very bad sinus infection resulting in a 10 day round of Augmentin, my last dose was on April 14th or 15th.. I arrived home on April 16th and have been sexually active ever since. I was due to start my placebo pills the week of April 20th. I never got it. Now I have low back pain, occasional heart burn, and tummy pressures. Is it possible that I ovulated late and possible became pregnant? Ive also had 3 neg dollar store tests.