Pregnant ? Please help.

Kourtnyi
Hi everyone please help me,
​So I had a miscarriage on April 26, 2014. I was 11w 6d, I went into labor and had no clue, he came out after 3 hours along with most of the placenta. I was put on methergine and a few days later the bleeding and pain stopped. I went to the doctor and everything was fine and my pregnancy symptoms were gone. That day I had unprotected sex (not intentionally trying to get pregnant) and for 3 days now my boobs started aching again and I have been urinating a lot so I took a pregnancy test and to my surprise it was positive. Could I be pregnant 4 weeks after my mc ?