It has been reported that some patients have been misdiagnosed with Irritable Bowel Syndrome, when in fact the correct diagnosis in their specific case was Gallstones.
Gallstones are crystalised deposits of digestive fluid called bile that forms in the gallbladder. Gallstones may cause no symptoms, if they do the gallbladder will need to be removed. Symptoms that indicate this include sudden and rapid pain in the upper right quadrant of the abdomen, back pain between your shoulder blades, or in your right shoulder, nausea and vomiting. As the only real symptom is severe pain, gallstones can be mistaken for a heart attack, peptic ulcer or gastroenteritis.