Sudden aggressive rat

I have 3 male rats, two brothers, Rocky and Marley, who are nearly a year old and Zuma who's 7 months old (Rocky's son from an oops litter).
They've always got on so well, always cuddled and have been the sweetest boys.

But now, Rocky is acting so aggressive. He tries to stop the other two getting food and will take it from them, he pushes Zuma off the ledge when he's trying to drink and had nipped Marley.

Today has taken this to another level! Rocky had bitten Marley twice, once on the base of his tail and once on his back. It was completely un-provoked. I took Rocky out the cage to give the other two some peace and he done his usual sniff around the sofa, crawl over me and lick my fingers. But then he climbed up on my shoulder (his favourite place) and bit my ear! It wasn't just a little nip, I heard the crunch and he drew blood so I know he meant it. I took him off my shoulder and he was so puffed up, his fur was all on end.

I'm at a loss on what to do with my boy, none of my other rats (have 11 in total) have ever done such a thing. I feel like taking him to the adoption centre but I know that's out of shock and fear that he'd do something worse. For now, he's in the clean out cage which I can't keep him in. Please help!

How long have Rocky and each of the others lived with you, and how long have they lived together?
Rocky may be ill, may be in pain, so I would suggest you see if you can notice any other changes in his behaviour, in his weight, food intake, breathing, etc
He may need a neuter with a good vet who has the knowledge and experience to do it safely, because male aggression is usually hormonal.

Can you post a video of him to youtube and then post the link on here?

How big is your cages and what sorts of things do you have in it?
Have there been any changes? new smells? have you been handling any other animals etc?
Do you have any other pets?

I would get Rocky neutered asap.

How is he now?