I agree get the leg seen to.. but go back to basic training -

keep giving him commands and rewarding him, when he does them.

stay is great for asserting your authority ... make him stay and put some treat in front of him but only let him have it after 30 seconds or so, don't let him get it if he doesn't stay long enough though.

give him some boundaries too don't let him on sofa, bed etc while he's going through this dominant period.

i would also just like to add - ensure that you don't encourage his dominant/aggressive behaviour.

we recently did a rehoming assessment for a akita which was being aggressive towards the children in the family and any strangers that came into the house, things were so bad that the mother had to leave the kids a drink in living room for when they came home from school, because if they went into the kitchen, the dog would attack them.

the thing is, when the dog was aggressive the owners would say "calm down, good boy good boy" etc and were completely encouraging his behaviour, the dog was sat growling at the kids when they came in the house and the owners were sat fussing the dog, not realising that they were rewarding him for growling at the kids.

so whatever you do don't fuss him, but ignore him when he is aggressive towards you. or send him out.