Spotting at 4 DPO

Hey guys, i have a situation here. So I spotted brownish red blood 4 DPO which was on 17th Aug. It NEVER happens to me. Last night, we had sex after so many days. When I cleaned myself, I noticed some brown blood. Then today morning, i had a discharge of brown blood. I thought AF started, but now it's gone. Nothing at all. Are there any chances of me being pregnant? Please help. Really worried because i had a D&C; in march and now we are trying again. Please please reply. :(