What can I eat/drink if I'm throwing up everything including water because of a stomach bug?

You need to take one sip of either water or flat, room temperature clear/white soda every 15 minutes. Some of it may stay down, some may come back up. If it stays down for one hour, the next hour, you increase it to 2 sips every 15 minutes and keep advancing until all is staying down. Do NOT put any food in your stomach until you have not vomited for several hours and then start with saltine crackers. Wait at least an hour to see if they are going to stay down and then gradually, in small amounts, advance your diet. Because you have been vomiting, expect some diarrhea for the next couple of days because that is how your body gets rid of the offending "bug" out of your system.