From your symptoms it sounds like you have acute
inflammation of the lining of the stomach or even
an ulcer. Think back and see if you ate any bad food
like contaminated poultry or dairy products. If you used
any pain killers like aspirin
or similar NSAIDS,
they can cause acute inflammation. Especially,nausea, vomiting
pain worsening after food makes the possibility of "Gastritis"
on top of the list. If you also start having dirrhea with this
is a distinct possibility.
Try to stay on clear liquids like apple juice or white grape juice.
Bland diet with rice, mashed potato, pasta without much
seasoning will be O.K. if you can tolerate it.
Take over the counter Cimetadine or Ranitidine
or even Omeprazole
twice a day till symptoms get better. If you continue to have severe
pain, vomiting, you may need intravenous fluids and may be further
work up to include blood ,stool and x-ray studies of your stomach.
Hope I have given you what the possibilities are.
I wish you well.