Hello. Brown discharge is not due to Anal sex. It is due to the Ipill you have taken to avoid pregnancy on the day of sex. It is very usual to have the brown discharge after taking emergency contraceptive pill. Since the Emergency contraceptive pill disrupts the normal hormonal signaling that regulates the menstrual cycle, it is not surprising that bleeding irregularities are common. This can result in spotting, having a period that comes up to a week early or even late. It can also result in a period that is lighter or heavier than normal. In most cases, the first menstrual period after taking emergency contraception will occur within 1 week of the usual timing. In cases where the period is delayed, this can obviously be of great concern for women fearing pregnancy. The morning after pill will not interfere with pregnancy tests, and a urinary pregnancy test can be used for reassurance after a missed period Thus nothing to worry about this. If you miss the next period, then you have to check the HPT. Hope this helps. Please write back for further queries. Wishing you a good health.