I need help

Uno is only sweet and cuddly when he's tired...other than that all he wants to do is bite me......Today was the WORST...I was holding him and giving him a lil' scratch behind the ears and he bit my lip

I seriously almost started crying...Not because it hurt, but because i'm just so frustrated with this....I can't hold my puppy, he's not sweet and cuddly...he's being a lil monster. He turned 12 wks today and my fingers can't take it anymore....