Hi, Thanks for writing to Health Care Magic, I am Dr Asad Riaz, I have closely read your question and I understand your concerns, I will hereby guide you regarding your health related problem. IBS is a syndrome in which patient have either constipation or diarhea n bloating abdominal cramps, in case of diarheal predominant IBS patient bowel unable to absorb proper amount of at n protein result deficiency of these nutrients .. protein is needed so that body can maintain proper pressure in side the vessel so that fluid donor leak outside that causes sweling like I m ur case leg sweling(edema)..If u were mine patient I would like to give u some antidiarheal agents n do some test to check ur protein levels n then treat u properly.. I hope this answered your question, if you have more feel free to ask. Regards. Dr.Asad Riaz. General and Family Physician..