Why is my neutered rabbit aggessive?

I've had my two rabbits for eight months and they were good boys up until they were four months of age. One of my rabbits Jasper, was having behavioral problems and was attacking my other rabbit Chester. Chester wasn't doing anything except for Jasper. So we got both of them neutered. Jasper had a fast recovery and was jumping around the very day of the operation. It was a little harder for Chester, but he recovered with no problems. About a few weeks after the surgery, Chester began to be more aggressive . It started with just growling in the cage whenever he got picked up but he's been neutered for more than four months and now he's biting, scratching, growling and pouting all the time! He used to be a sweet little guy who would love to kiss and literally give hugs, but now he's a brat! If anyone has any answer or any experience in this department it would be VERY much appreciated, and if you could, no jokes. I really need an answer soon! Thanks!