Good day. I've been getting nauseous and throwing up for almost 6 months now. It happens when I drink soda or juice and it's sometimes caused by certain food. I'm having trouble eating these days because I'm scared of eating the wrong thing and throwing up. I went to see a doctor a few weeks ago and she said I might have alcer. For the past two days, I woke up to being nauseous. But when I try throwing up, only saliva comes out. So I want to know what causes such?