These are some meds which work in diarrhoea and vomiting;
Loperamide 2mg capsules up to 8 in 24hours for diarrhoea
Codeine 15mg - 30mg up to four times daily for diarrhoea
Mebeverine 135mg tablets three times daily for spasm
Hyoscine hydrobromide 10mg four times daily for spasm
Prochloperazine or domperidone three times daily for nausea
Once the bowel is upset, it then has problems digesting milk.
Avoid milk products for 24 hours
Drink plenty of water
Eat small bland meals
Eat fresh boiled rice as this slows down gastric transit
Cramping can be helped by dimethicone or peppermint oil capsules. Peppermint tea is really good to help settle the digestive tract.
Ensure you keep fluid levels up. If you do all the above, it should settle down in 24 - 48 hours however if you have been abroad recently, or there is blood, mucus or pus in the stool, then see your doctor. Any severe pain or temperature should also be reason to contact the doctor sooner.
Does this help?