Yes pro-kolin is good, if i was going to withhold food it wouldnt be for 24 hrs in a young pup i just feel its to long , and would always have fresh water available which i change after every drink while loose , in fact i'm not sure to with holdfood is good,there tends to be various thoughts on this .
If necessary i feed mashed potato no milk or butter of course and boiled white fish small amounts several times a day ,increasing if tummy seems ok until gradually going back onto normal diet