Hi
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It could be a case of food poisoning due to something you ate. Take an OTC lactobacillus preparation (probiotics) and yoghurt with your meals. Drink plenty of fluids (clear soups, water, ORS in water, lemonade). Eat light, do not stay hungry but eat simple things like toast, porridge, cereals, crackers, banana, rice, peeled apple, etc. Take over the counter antacid and antiemetic (this SOS for vomiting). Watch out for a day or two with this treatment. If it does not help, discuss this with your doctor and get yourself examined. Other than this, yes, pregnancy is a possibility. Take care!
Gastro intenstinal problems. It's probably just gas.