I just had one of those. I have been constipated for a week from taking vicodin (just had a tonsillectomy). I took 2 tblspn of milk of magnesia to unconstipate myself, and 2 hours later, I went into the bathroom and was in there for 20 min with the worst cramping and diarehea ever. It beat my food poisoning diarehea that I had weeks ago and my stomach pains were so bad that I had to lean over with my arms around my stomach and close my eyes. I started breathing really heavily to calm myself down. It was horrific, and even afterwards I still had excrutiating stomach pains. I had to take a tspn of vicodin (thus probably constipating me again) and lay down for the last 2 hours. I feel your pain trust me!