Hello, Thanks for sharing your health concern with us. I have gone through your query and would like to offer my opinion. If you had the intercourse during the fertile period of your cycle, which is the ovulation period that falls two weeks prior to the onset of the next cycle, your chances of pregnancy are high. Else, your current symptoms can be attributed to an infection of the lower urinary tract. Brown spotting indicates old bleeding. Implantation bleeding is a fresh bleed and is seen around the expected period. A HPT/blood test followed by a trans-vaginal/pelvic sonogram and urinalysis clarify the situation. Hope this helps.