Nausea In The Morning With Lightheadedness, Hot Flashes, Recurring Vomiting Sensation That Subsides With A Headache, Relief On Lying Down. What Is The Cause?

Lately i ve been having really bad nausea in the morning. Sometimes it happens very quickly without warning while i m on a bus and sometimes i wake up sick. I start feeling lightheaded, hot flashes, nausea and just the feeling of dying. When i m horizontal (a.k.a laying down) i can control the nausea and it calms down but the moment my upper body is up vertically then the lightheaded and nausea come back. It doesn t even matter what i ate, if anything, even if there s nothing to vomit i ll still vomit liquid. The vomiting sensation will come back again and again even if i already threw up everything. Usually after a couple of hours it calms down and leaving me just a headache . Last time i went to the doctor i never got an answer.