So about 4 weeks ago I had unprotected sex with my boyfriend. I am currently on the pill but forgot to take it that night and the following day. Sometimes i have my period and sometimes I dont with this birth control but i havent had one since I had sex with him and I did the month before. I took a test 2 weeks after it happened and it came out negative. But the last couple of days I have been feeling very nauseus and had a really bad headache that comes and goes through the day. I also havent had much of a appetite either and have been having some mood swings. Could I be pregnant and should I take another test?