Why would a pottypad trained 2 year old dog start peeing and pooping on the carpet and floor?

I have two 2 year old dogs that have been trained to go on a pee pad. The last two months, one of them has started peeing and pooping throughout the house, anywhere but on the pad. We praise him when he goes on the pad and scold him when he goes on the floor or carpet. The two dogs get along great, but he is the dominant one and is very jealous. I have tried to clean pee spots to help with scent. What should I try?