Headache and vomiting. Please help me.!

Hi. I have headaches. I visited a neurologist he said I have migraine. I am taking medicines from last 5 years. My condition has improved by 50 %. Now I have headaches to a less extent, Once or twice a month. But I have vomiting problem. It's not a digestion problem. But I think it is a neurological problem. Comparing to other people, when a person has to give a speech or present in front of many people or when he has to go on stage and perform something or say something he feels like an urge to urinate. But in my case I vomit When I have to go on stage, give an examination, give speech in front of many people, perform something in front of people my saliva reduces and my mouth becomes dry and I vomit. If I haven't ate anything before still some liquid Will come out of my stomach. I had tried many times to control vomit but I failed Everytime. Please help me....!!!!