I'm thirteen weeks pregnant and have had constant vomitting and headache since start of pregnancy. I have been taking tylenol, (acetaminophen) should I go to er?

See your doctor. These symptoms can only be adequately diagnosed only after a thorough evaluation by your doctor. This may include labs and other satudies. Once all of the information is in, your doctor can let you know what's going on, and what to do to help you.