Hi ladies. I'm currently 20 weeks pregnant with identical twins. In the beginning of my pregnancy I had light nausea and heartburn. However today after walking (leisurely) for about 45 minutes I got extremely light headed and shortly after vomited. I had a light lunch to settle myself and provide some nutrients for these babies and now about 30 minutes after that I vomited again. I am nervous and hoping that everything is okay with these babies. Has anyone experienced these symptoms around 20 weeks?