Verified answer

period cramps (if a girl), stomach flu/acid reflex, not much fiber it could be any of those if its cramps then use a heating pad if its a stomach flu a little of medicine should help and just eat fiber if its that problem or if nothing happens then try drinking soda or eating something that makes you well..gassy

It may be probably due to acidity.

probably just gas or constipation, have some fiber one or someting, you should be feeling better in no time.