If you are experiencing severe stomach cramps that extend to your back along with diarrhea, it is likely that you have caught a stomach virus that is going around. In this situation, it is best to rest and drink plenty of water. If the diarrhea lasts for more than 4 days, if there is blood in your stool, or if you show signs of dehydration, such as very dry lips, wrinkled skin, or extreme drowsiness, it is important to seek medical attention. Otherwise, it is recommended to rest at home and stay hydrated.