My 3 month puppy is becoming very aggressive, jumping, biting and barking. Especially in the evenings I am getting very frustrated trying to figure out why and how to stop him.
Any suggestions greatly appreciated.
Puppies often do get hyper in the evening, it's a bit like toddlers acting up when they are overtired.
If you can, prevent it by anticipating the time it is likely to happen and settle him with something to do, like lick frozen food out of a Kong toy.
But he really isn't being aggressive. This is just an extension of the boisterous play he had with his littermates but he needs to learn this is not how to play with humans. Some people find a sharp 'ouch' works but it can just ramp up the excitement. Some people find putting a toy in the dog's mouth works, others find the puppy is still more interested in nipping hands. My preferred method is to teach him that teeth on skin equals end of fun. So as soon as he makes contact, walk out of the room for a few moments. As long as the whole family is consistent - do it immediately and do it every time - he will learn. You could use a house line to draw him away, which keeps your hands both out of reach and also keeps hands for only good things.
There is also something called ”extinction burst” that you should be aware of. This is when a behaviour that used to get attention no longer works for the dog so he tries it all the harder and it seems like things are getting worse, not better. This is good, because it means that what you are doing is starting to work.
I have been trying all these things, but like you said it may be the extinction burst. The constant attention seeking hopefully will slow down. I have enrolled him in puppy training and am hoping that too will improve behaviors.