I have periods and having unusual pains in my stomach?

You must be writing: for somebody else. Of course a 27 year old male doesn't have periods. "Unusual pain" in the stomach could have MANY causes: inflammation of the stomach lining (gastritis or ulcer), reflux of acid stomach contents into esophagus, gall bladder problems, bowel obstruction, appendicitis, constipation, irritable bowel syndrome, etc. The only way to get a diagnosis is to have a professional examine you.