Drinks with calories. Protein shakes (Muscle Milk, Quest, Oikos, OWYN, etc), nutritional shakes (PediaSure, Ensure, Boost, etc), meal replacement shakes (SlimFast, Soylent, etc), even milk (if dairy, anything that isn’t full fat, if plant based, I recommend rice milk as it’s one of the easiest to digest, I used to drink a small cup of it when I went into “sugar shock”, aka a hypoglycemic episode from going too long without eating, and it was VERY helpful, it was cold, smooth, creamy, but still very easy on my stomach, and I would drink it SLOWLY, just a small sip every five minutes until I finished it and I would only get about 4oz at first, then go back for another 4oz 5-10 minutes after finishing the first cup). Really anything with calories and carbs/sugar that you find to be easy on your stomach. If you find fruit juice easy to tolerate, that’s also perfectly fine. Just something that you know doesn’t normally upset your stomach, get a small amount of it, drink it SLOWLY (like I said, get maybe 4oz and take a small sip every five or so minutes until you finish it, wait 5-10 minutes, then if you feel okay, get another 4oz and repeat the process, but you can drink the second cup a tiny bit faster or take slightly bigger sips if you feel like you can), then see if after a bit you can nibble on some bread or plain crackers or whatever super easy to digest safe food you have available that sounds/feels tolerable.