Hallow Dear, Two days after the period, there is no egg present to get fertilized; hence the probability of pregnancy due to this intercourse is almost nil. Egg is released (ovulation) 14 days prior to the next expected menses. Life of egg is 24 hours while the sperms are active for 72 hours. Hence a period of about one week is considered as fertile period. Your intercourse was far away from this period. So I feel, there is no necessity to be worried about pregnancy. Still, if you miss period, you may get pregnancy test done after 8-10 days pf missed period; earlier these tests may give false negative results. Alternatively you may opt for Beta hCG test which gives reliable results even few days before missing period. Brown discharge always denotes old blood. Since you had intercourse just 2 days after menses, it is likely that you had some left over blood trickling out. All your other symptoms are definitely not due to pregnancy. Nausea starts showing up about 10 days after missed period. Nausea and headache together suggest hyperacidity. Some protonpump inhibitor antacid like Pantoprazole will help you. The other symptoms to me appear to be due to stress of unwanted pregnancy. However, you may take some painkiller for headache. If it still persisits, please report to the Physician. I hope this helps you. Dr. Nishikant Shrotri