im 18 yrs. old male, and every 40 days or so... i start to slowly cramp all over stomach, and it get worse and worse untill, i cant sit or lay down, and this happens to me for about 2-3 hrs. and the past couple of occasions i also vomited during this stage.... after the couple of hrs.. the pain than goes down to my intestine area and i have very sharp pains and this continues for 2 days or so... getting better with time, but i dont know why it happens... i have gotten a endoscopy and a sigmoidscopy done and in the sigmoidscopy the GI said that ur colon is very clean. and the endoscopy showed a small hernia and some gastritis... any help would be highly appreciated