Take an OTC lactobacillus preparation and yoghurt with your meals. Drink plenty
of fluids. Eat light, do not
stay hungry but eat simple things like toast, porridge, cereals, crackers etc. Take ORS. Take over the counter antacid and antiemetic (this SOS for vomiting). Watch out for a day or two with this treatment.
If still the symptoms persist, then you may need an antibiotic for the gut and would need to see a doctor.