I only just read this today so I hope that Xavier is better by now and has his appetite back. My son is 2yo and just got over a stomach bug that lasted about a week. He had a very weak appetite for quite a few days after this. I kept offering him water throughout to stop him getting dehydrated. At first he just had dry toast cut up small, then with a very light spread of margerine. I try and offer things that are light on the stomach, avoid rich and dairy food and small portions more frequently. Sorry not terribly helpful, but I hope your lo is already better.