Great that you have a solution. But if you suspect yeast, then his diet really needs attention. Otherwise, it will be a case of treating the symptoms, but not dealing with the cause (which could be a diet too high carbs).
It’s still working and Zaba has gone home today. I told the tale to his Mum and she seemed to take it well. I mentioned the possibility of yeast and that his food may be too high in carbs.
We’ll see what happens but I feel really pleased that an answer seems to have been found.