My friend has been having stomach pains for about a year now.?

My friend is a 16-17 year old girl who has been experiencing really bad stomach pains for over a year now, she says it will go on one side and then be on another the next time, she says its not appendicitis and that lately it hadnt been acting up but just last night she had an episode that left her on the ground in agony barely stopping herself from screaming from the pain on her left side. She cant afford to go to a doctor but does anyone know if chronic pains like these are a sign of something serious?