I Have Had Diarrhoea For About 2 Months We Thought

I have had diarrhoea for about 2 months we thought it might be my medication called nexium 40mg so went to doctors and he reduced the dose to 20mg. Started the new dose on Saturday,so have been using it for 4 days there has been no lessening of symptoms. We were looking in my medication cupboard and found a drug called domperidone and wondered if I could use this instead of the nexium