Preetha,
Welcome to the MS forum. I am so sorry about your husbands health problems. You have heard from our most experienced member (Uppitycats). I don't know too much about Crohn's or remicade. It sounds like the remicade may have been the culprit. You have asked some really good questions but I really think these are question for your husband's doctors. I would contact them right away and pose those very good questions. I am assuming you have asked these same questions on the Crohn's board. You are more than welcome here but I think you will find more experience with remicade there. Please keep us posted as to how he is doing. I wish you and your husband the best of luck.
Love and prayers,