I have suffered from acute stomach pain and diarrhoea on and off for years. It has a definite link to stress and anxiety. I have been referred all over the place but the only thing that really seems to help is taking multi billion friendly bacteria to boost the guts ability to cope.
This was recommended by a dietician who told me that if you get a stomach infection of any sort the natural bacteria become depleted in fighting the disease. Then afterwards they are sometimes not built up again and leave your gut struggling to cope.
You can try the yoghurts but they only have limited effect for me but you can also buy multi billion bacteria in health food shops. At worst they will not do you any harm and for me they work like magic. I now keep a supply and if the cramps start again I'm straight back on them.