I was taking Calcium tablets and vitd3 seperately but stopped as they were upsetting my stomach. I thought it could be the uncoated calcium so I bought some chewable type with vit d already added. Within a day my tum was bad again, bloating, bad indigestion, nausea, next day the same just as bad. I stopped taking them and all ok. I do have a sensitive tum and take omeprazole which usually keeps it under control. Perhaps I have enough calcium in my system? Anyone have any experience of this?