Thanks everyone
I've been to see Alfie, they said he has been very quiet and withdrawn but I think he was just unhappy being there. He hadn't eaten up until me going but he ate a full bowl whilst I was there
He did his usual headbutting and dribbling against my face so he's feeling a lot better and was pleased to see his mum
He's been taken out of the Oxygen tank and his breathing is a lot better and his colour is nearly normal now. They haven't got the foggiest as to what's caused it but they will be keeping him in over the weekend to monitor him, and if he has another breathing attack, the machine is there which to be honest is a godsend......the difference in his breathing last night after just a few minutes was brilliant so whatever the cost, it's worth it. I mentioned to the vet about a possible clot or possibly an asthma attack.....they couldn't rule either out, but may never know. I'm sooo relieved it looks like he's going to be okay....I've been worried sick all day about him, he's one of the sweetest gentlest cats I have and I couldn't bear anything happening to him. Poor Sally was looking for him this morning, I think she'll be just as relieved as me when he comes home.