Hi thanks for asking question.
Here are few possibilities in your case.
1.The first strong possibility is of
peptic ulcer.You should take pentoprazole for few days.Mostly within 2 week it will heal.
2.The other possibility is
gastroenteritis.It may be because of taking outside food.antibiotic like oflixacin and
ornidazole combination drug is helpful.
Meanwhile take semi solid diet with fruits.
Drink water more.
Avoid smoking if you have habit of it.
During night shift avoid excess tea.
The above treatment definetly help you.
If still no benefit then
ultrasound examination will be helpful.Still
endoscopy examination may needed if not improving.
I hope you will be alright within few days.
Wish you good health.
Dr.Parth goswami