I don't have any response so I will try and answer based on the information given.
You can treat this with Pepto-Bismol syrup and Nexium 20mg once a day.
If this is a female and there is any chance of pregnancy, don't take them.
Otherwise, you can get them from the pharmacy without a prescription.
The most important part of the treatment however is going to be good fluid hydration.
This can be done with oral rehydration salts/Pedialyte/Gatorade/clear juices as per your preference.
Some other measures that will help:
Also, take one serving of yogurt made from active cultures a day.
Avoid more than 100 mg of caffeine a day.
Avoid any alcoholic beverages.
Meals should be in small quantity, but more frequent.
Avoid high-fat, oily, or spicy foods till this resolves.
Bananas, rice, and apple are good.
If the person does not feel any better in a few days, they should go and be checked in person by their primary Dr.
I hope this helps?
Please let me know if you have any questions about this.