How do I stop my puppy from attacking me when he pees inside?

My puppy is a Bichon x Japanese Chin, he is 10 months old. When he use to pee inside we would yell at him and he would get all sad and depressed and he would lay in a corner. Ever since he had to go to the vet to get shaved (he had to be anesthetized), he has been getting really agro and aggressive when he pees inside. He gets aggressive and we don't even yell at him. Today he peed inside (He is getting better at not peeing inside except for this time) and i cleaned it up, picked him up, patted him, he was starting to get angry, I tried to calm him down, He wouldn't so I gave him some treats, then he turned around and really aggressively bit my finger and bit my arm while I was putting him down. My whole arm went numb and my finger is bleeding and throbbing. Could it be infected? And how do I stop my puppy from attacking me like this?