I tend to have very bad cramps once i have just eaten beed. why does that happen?

That's not good: Cramps tend to be painful, or very annoying if not painful. One's doctor can evaluate. A patient should write down her symptoms on a calendar, describing the cramps... such as where in the body they are, when do they start, what makes them better, what makes them worse, etc... Also, the doctor will ask what foods, drinks, or medications are associated with the cramps. Tell doctor what "beed" is.