Was fine then sudden pressure in pit of stomach, severe nausea, bad gagging, no fever, slight bloating, feeling very tired and dizzy at times.

See MD asap: Sorry you are not feeling well. You need a pregnancy test and full history and physical. Left upper quadrant pain with dizziness I think some labs are appropriate to check your complete blood count and serology for ulcers caused by H. Pylori, a rectal exam to rule out bleeding. Any dark tarry stools or spitting up blood? Vital signs and full exam meds surgery history all needed. If very dizzy ER