help please. boy turned aggressive.

I have a three yr old boy and over past two months if he gets told off- (vocally) he growls and goes stiff.
Over the past two days he has beared hes teeth to two male family members- because he was told to get off the sofa.
It is so out of character for him and i notice he never has done this to me, but i can not understand why he has changed.
Recently he has got very protective over hes bones also
Could getting him neutered be the answer?

Neutering may or may not help, but I would be looking at changing the behaviour before even considering neutering.

Has anything happened to make him more 'possessive' or territorial? Does he have a clean bill of health from the vets?

Could the behaviour be linked to any loud noises or disturbances?

My boy is not a fan of sudden noise, he has deffo been stressed about fireworks this week.
He is in full health.
I cant think of any time that something could of made him more possessive. He really is treated well.

Has the behaviour started since the fireworks have been going off?

Also, exactly what happened when he growled at the male family members?

Has he ever shown any food aggression etc before?

Sorry for all the questions. 

Id say it has got worse since the fireworks.
He is not a greedy dog- you can put your face in hes food bowl while he eats n he dont
Bat an eyelid.
When is growling and snarling at the family member they moved away and i told the dog to get in hes bed- which he did but he sat there shaking. 2 mins later him was fine. He has never beared hes teeth before though :/

This has also happened in a similar way to Vinnie. He has been so scared of the fireworks and has growled whilst on our walks at a few dogs which he never does.
I think it may be fear aggression, and hoping it will gradually get back to normal. 

Sounds like he is testing how far he can go it sounds like dominance to me.

Hayley if thats the case, what would you suggest?

*bump*