Firstly - you do not have an aggressive puppy. It is completely normal for puppies to be like little pihranas - some are worse than others, but they all do it. And it does not mean you are going to have an aggressive adult dog.
How long have you had him? You say a few weeks ago - that implies you may have got him before he was 8 weeks old. This isn't recommended, as up till this age, they are still learning form their littermates - this can make teaching bite inhibition more difficult, but not impossible.
You really need consistency to teach your pup how to interact with people - it is not something they inherrently know, but rather something they rely on you to teach them. Our pup is now 10 months old, and we were first time puppy owners when we got her - the learning curve is very very steep, but you do get there - honestly.
I'll summarise what we eventually found worked well with Honey - others find slightly different approaches worked for them - the key is deciding what you will do and sticking to it.
Firstly - We started with clicker training from day 1 - this might not sound relevent to a biting problem, but it helped acheive a good relationship, and made Honey think (thus tiring her out mentally). It also meant we quickly had a reasonably reliable "Sit" command - it is more difficult to hang off someone's sleeves (or skin) if your bum in on the floor!!
Secondly - We had lots of toys - but also lots of cardboard strewn around. This meant there was plenty of things for her to "attack". Puppies play and explore by using their teeth, and this need to happen so that they can develop into well adjusted adult dogs.
Thirdly - Whenever she made contact with us (with her teeth) we let out a yelp (similar to what she would do if we trod on her tail!!) and stopped what we were doing very briefly. If it occured again we again gave the yelp and walked away from her (when older we would shut a door between us to reinforce this). We only ignored her for a few seconds, then went back as is nothing had happened. This, to us, mimicked what her littermates would do if she had overstepped the mark with them. It was very tiring, and I, spent a lot of time in tears, wondering if we could ever get through it.
Fourthly - we did play lots of tug games with her - some people disagree with tug games, but Honey loved them (and still does). She has a peice of rope which was the main tug toy - and she would growl and wrestle quite happily. As she got older, we would get her to sit before playing, and then interrupt play with a few sits. We are now at the point where she can be playing tug, shaking away and I say "Give" and she will stop and drop the toy. She will then sit and wait until she is given permission to play again!!!
I do recall that at about 10 weeks, Honey really didn't like being stroked - it's not something that is natural for dogs to accept. Start when your pup is relaxed, and just stroke once, then give a treat reward - he will soon learn that human contact is a good thing!!
Once he is happy with a small stroke, you can build it up. But, to be honest, it is only in the last couple of months that Honey has really started to enjoy being fussed.
I hope this helps you to beleive that you have not bought a monster - just a pup. I know it is hard, but please try not to be scared of him - he will pick up on this and become more unsettled as a result. A pup needs to know it is safe and protected. It needs consistent boundaries for behaviour. It needs regular training, play and socialisation. It needs to learn how to use its teeth. It will take a vast amount of patience, and there will be times when you feel you are at the end of your tether - but it does get better and at the end of it all you will have a dog you are proud of and who adores you!!
