Missed Birth Control Could I be Pregnant ? 10pts?

Im on birth control pills been on them for 6 months now. I had unprotected sex where he came in me and the next two days I forgot to take my pill. So I missed two pills. I woke up and took one just because I was scared I could get pregnant. I am having severe cramps and pain. Everything I eat I feel like I wanna vomit, and now im having brown discharge with some blood. I just feel awful. I took a pregnancy test but its negative. Should I take another one ?? I had sex Wednesday night so its only been like 4 days. Is it to soon to even get pregnant ?? My last period came on the 9the of November and only lasted about 4 days and it was on real light.