You didn't mention since how long you are experiencing this problem.
If it is of recent origin, it may be some kind of gastric irritation.
Check the colour of urine.
If it is yellow, & if there is any pain in abdomen, with fever, it may be liver involvement.
You may have to go for blood & urine checkup & also ultrasound scanning of abdomen & pelvis.
If there is chill with fever, it may be some kind of infective fever.
You can please consult in person