Had unprotected sex on dec 25th ,2017 .I am on contraceptives but was not having them since a few days and also not on that day if sex. I got my period on time on 14th jan, 2018 as it happens. Started my contraceptive again on third day of period which is 16th jan. But today I got a brown tiny spot on my underwear. Was going through a little stress this month. Am I safe? What can be the reasons for this spot? I am still on my contraceptives n had not done sex after 25th dec, 2017. No sex after that day till now.