So we were on vacation this past week and had sex almost everyday. I ended my period on Tuesday the 9th and the following Tuesday the 16th we were on our way home and I was so sick that morning. Felt like I had to vomit but had to make myself to relieve myself before we got on the plane. What would this be from? Everyone we were with said that it was morning sickness but I disagree since the tested and it came back negative. Any answers?