My dad is 80 years old and has just been diagnosed with severe heart disease. He is waiting to get by pass surgery. He is not well and has developed constant stomach upset over the last 2 days. Antiacids give him relief but the discomfort returns. It happens regardless of what he eats. Could this be a brewing heart attack? He has had a moderate(silent) heartatrack and a mild stroke in the last 5 months.