Maybe he feels like his status in the house is beeing threatened with all of the new people coming lately

It sounds like this has not been a fun time for him. If his behaviour changed after your cousin came then it sounds like something might have happened; dogs don't act out for no reason.
Biting you is serious though and should not be tolerated. If he has continually challenged your doninant status then you need to make some changes. If you take on the leadership/dominant dog role he will follow and respect you. Right now he does not respect you. Do not let him get away with bad or unacceptable behaviour. Never show fear if a dog bites you because if they see you are scared then they know they can challenge you and will keep doing it and will probably bite you again. You have to gain control now. How obedient is he? An obedient dog will usually have respect for you and not challenge your leadership.
I would suggest when he starts becoming aggressive correct the behaviour right away by saying in a loud firm voice NO. You can also put him on a time out in a crate or a 'naughty place' so he knows he did bad. Never reward bad/aggressive behaviour. If he starts becoming aggressive with treats do not give them to him. This only re-enforces and rewards the bad behaviour by giving treats. If he acts nicely then you can give him a treat. A good thing to do is always make him work for the treat wether it be good behaviour or obeying a command such as sit or shake. This will re-enforce good and obedient behaviour. I always do this with my dog, give her a command such as sit and shake, before I give the treat so she is being reward for good behaviour and being obedient and she knows she has to earn it and it is not just given to her

Also, practicing commands such as sit, shake, stay will help him become obedient and show that you are the dominant dog which will help you gain his respect
Another way to approach it if the behaviour doesn't get better is take him to a trainer where you can work one on one to solve the behaviour issues. They will know exactly what is going on and how to correct the situation
