Severe cramps in the stomach. This infection results in the release of Shiga toxin. This erodes the lining of the large intestine, and will ultimately cause ulcers. This can result in intense pain, with a burning sensation, and stomach cramps. It is not uncommon for a person to have to maintain a fetal position from the pain, which is so agonizing that it can completely prevent the sufferer from engaging in any activity whatsoever. Blood in the stools can be expected within a day of a person’s suffering such cramps.