I took my first depo shot in May and I do not take the next one until August. I recently had unprotected sex about two weeks ago. At the time I took an antibotic but I only took it once, the day we had sex. Lately I been feeling kind of strange: tired, stomach hurting, back & headaches. Can I possibly be pregnant?

Since you had sex and no form of birth control is 100% effective, yes, you could be pregnant. The only way to know for sure is to test using first morning urine after your next period is late.