I had unpotected sex 2 & 1/2 weeks ago during the time my menstrual was on ( sorry if too much info ) and my period went off immediately the next day . I now feel extremely nauseated in the evenings throughout the night. I have not actually vomited but I really feel that will help. I'm really worried now because I have been having light pink discharge for the last 2 days so I took a pregnancy test and it came out negative . I have no tenderness in my breast which would be easy to tell since I have really large breast and I have had no lower cramping nor pain except in my right lower back when I stand a long time at work. My boyfriend thought it was my medicine causing this since I have really bad skin ( allegra , antibiotics, and was taking diet pills but I stopped when I thought they were causing the nausea .) I seriously need to figure out if someone knows what is possibly wrong cause my doctor warned me about the serious side effects of my medication and I would never forgive myself if I had hurt my baby ......please help .