i had a stomach problem last week
i did what i do for my daughter (shes fed with a high cal formula milk)
i went to fluids only during the day, fluids are very important but you know this im sure. i wasnt really holding the water down but im sure some would be absorbed.
when it got to the evening and i hadnt been sick in a hour then i made a half shake but i used double the water to make it gentler on the tum. i managed to get in 2 packs a day that way for the next couple days (missing packs not advisable but couldnt get anymore in without it all coming back)
otherwise doctors sugest the BRAT diet to settle tums. Banana's, Rice (white), Appes (stewed), Toast (dry and white)