we need to know what kind of pain? sharp? stabbing? dull? constant? in which quadrant is the pain localized in?
when did the pain start? onset
how long? duration
alleviating and exacerbating factors? did you take anything you feel directly contributed to you feeling ill?
any nausea and/or vomiting ?
any jaundice? as in discoloration?
any tenderness?
how are the bowel movements?
have you had this sort of pain before?
any fever?
Have you traveled anywhere recently or changed your diet in any way?
if it is a simple case of food poisoning or over eating I'd recommend you get some charcoal from the pharmacy in capsular form and empty it in a glass of water and drink it... if you have answered yes to the latter questions starting with Nausea and vomiting then please go to the Emergency room as it can be a whole host of things from gall stones to appendicitis and no one is qualified to diagnose that over the web not even a doctor... You would really need to be seen
May Allah yishfeeki and 'Afeeki inshallah
let us know how you are first chance you get please.