Hi. Thanks for your query. Noted your history taking Imodium for diarrhea and then developed pseudo obstruction, fatigue, severe chills. The causes can be as follows: This is the untoward side effect of Imodium. It can be an actual infection of the intestines. Can be due to electrolyte imbalance. I would advise you the following: Get the clinical evaluation by a General Surgeon. Investigation like X-ray in the standing position. Ultrasonography. Barium studies if motility has become normal. Or a CT scan with contrast gives similar results. Blood tests, particularly for electrolytes as low potassium can cause similar problems. Once the cause is found, get this rectified.