I ended my last period on 7/7. I'm on birth control, but was taking antibiotics from about 7/6 to 7/12 for a sinus infection. Without thinking I had unprotected sex on or about 7/8 or 7/9. I started having what seem to be pregnancy symptoms (tender breasts, bloated abdomen, a slightly increased sensitivity to odors, etc) about 8-10 days later (don't remember exactly when they first started). I took a home test (First Response) on 7/25 and it was neg. My period should have come in the morning or early afternoon of 8/2, but didn't. Then yesterday, 8/3, in the early evening, I started spotting a brownish-red color. Today, 8/4, I'm still spotting and I have slight cramps similar to menstrual cramps. It's almost like a dark red or mahogany color, not like my normal period at all. Is it possible that it's implantation bleeding? And can I take another home test while bleeding? Or should I wait til it stops?