Hi, Kaitlyn, and welcome.
Well, it’s usually the other way around, where pre-neuter behavior is what you described and the aggression calms down after the surgery.
So, my first thought is he may have something wrong, and be in discomfort somewhere. Did you ask your vet about this? Has he been seen after the procedure? I would call the vet and describe it and possibly take him back for a look to see if it’s something physical. It may be unrelated to the neuter. At the least, he’s probably due for a nail trim so it wouldn’t be a waste to take him in.
If he is healthy, and his eating and pooping is regular and hasn’t changed as well, then you can try to slowly rebond with him. I would let him out in the same room with you, get on the floor to read or watch TV and ignore him. Let him come to you. When he does, talk calmly, don’t make a sudden move to grab him, and give him head pets if he’ll let you. Don’t come at him from above. Let him lower his head under your hand. Do that for a few days and see if it helps.
If you’re putting your hands into his cage to pet or feed him, he may be associating that with being pulled out for the vet. Clean and feed him while he’s out of his cage so you don’t appear to be invading his territory.
Oh – most important: it takes about 4 weeks for the hormones to settle down, so he might just not be at that point yet. But I’d call the vet first.