i had intercourse one week after my period, 3 days after the intercourse ibstarted getting brown vaginal discharge, it had no distinctive smell and not mucus, it lasted for 5 days in a riw and then stopped, my second period was supposed to arrive on the 13th october and till now it did not come, i made a home pregnancy test before the time of my period and 2 days after my period's schedueled timing and the results were negative.what is happening? could i be pregnant and the results are lying? what is wrong with me! could it be an infection? what are the chances that it is a serious one? could it be stress? pls help