Hi Alison,
Sorry I missed this, I hope Darwin is doing ok ?
Turkey mince with Rice, or potato if he likes it is a good alternative to Rice, Sweet potato is good for the tummy if the GA has upset him.
Hopefully he is over the worst of it by now, scrambled egg is nice and soft if he is still sore.
3 to 4 small meals a day and I would go from a couple of spoonfulls to a handful of the food and build from there, his poo should give you an indication if it's too much as it will be sloppy ( why do we always talk about poo when you have a dog !)
Love to you both x