Hello, I have gone through your query and understood the concern. If you have regular cycles and had the intercourse during the fertile days, your chances of conception are high. Implantation bleed is seen as a fresh bleed or spotting at the time of the expected period. If this spotting is seen soon after the intercourse, you have to exclude local causes like erosion, polyp or infections through a proper clinical evaluation. Brownish discharge suggests old blood. Sometimes, mid-cycle spotting is seen with ovulation. Please get a blood test for pregnancy ten days after the intercourse. A trans-vaginal sonogram can also be done to assess the situation. Hope this helps.