Do you have any canned potatoes in the house? If so, micro them, mash up and give asap. They will give instant energy, are easily absorbed, will soothe tummy, and they will help absorb nauseous tummy juices. In a pinch, even giving some saltines will help - the point is to get some carbs + energy + starchy in the tummy asap.
You can also give 1/2 tsp of Pepto.