I get stomach aches when i eat or random times. its not very painful endoscopy reveals nothing. could it be something serious? it happens a lot but, not that painful. could it be cancer?

Your body is talking to you. Listen and take good notes. I would focus on keeping track of what you eat and when in a diary till you figure it out. Then stop eating what you think is doing it and see.

Symptoms described suggest a functional issue, such as a spasm or colic. In the absence of other symptoms, such as weight loss for example, cancer appears unlikely, but cannot be ruled out either. Your gastroenterologist may help in follow up, keep a log of your symptoms/ ingested food/ bowel movements, etc.