L.B.
Sounds like a bug.
Water is good, also foods that are easy to digest - low fat, no grease - I tend to stick to oatmeal, cream of wheat, toast, etc. when I get a gastrointestinal bug.
And don't share cups and wash, wash hands etc. so you all don't spread it back around.
Gas-X, or any kind of simethicone, medication will help alleviate the gassy symptoms. Pepto and Immodium just bind you up for days, so stay away from those. Maybe take some ibuprofen for the cramping.
Feel better soon!