My cat is acting aggressive

[Kitty Pryde]

Hi,
Maybe someone here could help me out. My cat Logan is a six month old male domestic shorthair. He's always been very friendly towards me and sleeps in my room, although he does sometimes play a little roughly. I got him neutered during the week but he has recovered fine since then. He loves climbing around my room but I don't allow him on my locker and tonight when he tried climbing up I picked him up and put him on the floor again, then as I went to get ready for bed he suddenly attacked my feet and then jumped up on the bed and attacked my arms. When I pushed him away he kept coming back so I picked him up and put him in the sitting room and he started hissing at me. I let him out again about an hour later and he seemed to have calmed down and was purring and rubbing off my legs again but then when I picked him up to give him a cuddle he started making a weird noise kind of like a low hiss but his mouth was closed and he tensed up so I have had to lock him in a different room in case he attacks me again. Can anyone tell me why he might be behaving like this? Or how I might stop it?

Thanks.