
sorry, not much advice, but just to let you know you are not alone!!! My 7&half month old Mastiff, who I thought had finally grown out of this, bit my husband on the bum last night (in play, not aggresive) Some do take much longer to outgrow this than others

The best thing to do is try to stay calm & not shout, try & wind them down and offer them a suitable alternative (such as dog toy).
Hopefully somebody will have some better advice.