Edit: Sammy is all right now. The anti-histamines worked, so his facial swelling is definitely allergies of some kind. I have narrowed it down to two possibilities – one is prawns, which was one of the ingredients in cream sauce I made with the chicken for the cats, secondly could be dust or dust mites, as Sammy was found swollen after he came out from snoozing behind the refrigerator (where I cannot clean). I was extremely worried for him, but Sammy is extremely resilient and stayed strong and active throughout his allergy flare-up. Thank God he is okay now.
We couldn’t make it to the vet today. I gave Sammy some anti-histamines and his swelling has subsided – hope it gets better by tomorrow.
His diarrhoea is back again – looks like he has to go back on pure solid food, no milk, no cooked food. His allergy might be food allergy, so by scaling down his food variety might help eliminate the cause of his allergy, as well as help his poo to solidify again.
Hopefully he gets well in time to go to his new home.