jmaw2006,You need to stop the multi vitamin this will only upset your stomach more the vitamin a c e and magensium in them will give you pain and diarrhea.The calcium may be a good idea with vitamin D because it can calm the stomach and intestines but if you do not take it with food you will have more stomach ache. It can control the diarrhea though.Try to take at least a piece of toast when you take the calcium and take 1/2 tablet 3 times a day for 3 days and see if this helps but you need food.Linda