Abcess?

[LittleMissHumbuggery]

I've three cats, the youngest of which has been a little grumpy when picked up recently. I'd not thought much of it as none of them are really what you could call lap cats and will all tell you firmly to put them the hell down. However, went to shift him tonight and got a wet hand. Flipped him over and it looks like he has an abcess in, for want of a better word, his armpit. It looks huge:( there's no way I would have spotted it if I hadn't picked him up just so though, so I am wondering how long he has had it and how much pain he has been in.

I'm going to try to get him into the vets tomorrow, but am quite worried. He's about 4, and although he annoys the living chuff out of me at times I don't want him to be in pain:( Any ideas on what to expect? It's oozing puss in one or two places:(

Get him to the vets asap tomorrow - don't leave it. Ours twice had an abcess on his tail, the vet thought where another cat had bitten him and it had gone nasty. The first time it burst everywhere and wouldn't stop bleeding - it was quite scary.
He was quite ill with it - definitely under the weather for a few days - but the vet gave him antibiotics and we kept him in under close supervision and away from our other pets for about a week (which he hated) and it cleared up. It just gradually got smaller and not so nasty looking. We had to keep it clean, I seem to remember.
About a month later it came back - I suspect it hadn't cleared 100% the first time, so definitely worth getting a check up once you think he is all clear.
That was about 3 years ago and no trouble since, touch wood. But it was worrying at the time.

Thanks:) He has an appointment to be prodded in a bit, so we'll see how it goes. It looks like it has ruptured a little as it is weeping slightly, and there's no fur so he has been cleaning it like mad:(

Let us know how it went :)

Apologies for late reply.

He was doped up to the eyeballs with injectables and sent home with more. They didn't want to drain it as it is in a joint area. Vet was happy that he is keeping the site clean himself, and though it looks nasty she said that with time and antibiotics he should be able to fight it himself as he is young and otherwise healthy:) He's back there next week to have a follow-up prod, and to see if the cause of it is visible as the swelling ought to be much reduced by then. If it has been an infection due to him catching himself on something climbing then all will be fine, if it's a cyst then they might have to think about getting rid of the sac:(