What is the difference between a stomach ache and pms?

When and how much!: Pms usually occurs in the week or so before and ends within 1 - 2 days after a menstrual period starts. the most common physical symptoms include: bloating,  breast tenderness,  clumsiness,  constipation or diarrhea,  food cravings,  headache, diminished tolerance for noises and lights. Other symptoms can include: difficulty concentrating,  feeling sluggish, sad mood,  anxiety, and/or irritable mood.