First, congrats on the new baby! I just got done with this at my house... check around....I was just going through a poop crisis!
Second, your first mistake is allowing him to go on the pads. Get rid of them asap! He's confused. He used to be able to go in the house (on the pads) but now he gets yelled at? The best way to go is suffer the mistakes and only allow the dog to go outside. Also, get some good pet stain remover with enzymes to remove the smell of the urine. Otherwise, the pup will continue to pee in the same spot.
A few questions...
How old is he? Are you crate training him? Are you yelling at him when he does mess in the house?
Dogs respond to positive reinforcement, not negative. Are you rewarding him when he does go outside?
A few pointers:
The best thing to do is literally take him out every hour he is out with you. Watch for his signs. A lot of dogs will circle or sniff the ground. Don't let him out of your sight!
If he does mess in the house, don't yell at him. Remain unemotional. I know it's hard but if you get mad at him, he won't understand why and he might associate going potty anywhere with you being mad and instead of going outside, he might start to hide his pee and poo in the house. When you catch him in the act, quickly take him out, even if he won't go any more and repeat the same phrase over and over again. "Go pee pee" or something like that. Hopefully, soon he'll get it.
Crate training saved us I think. Do you have one? If not, get one. The dog then has a safe place to be if he is scared and dogs won't mess in their beds if they can help it so it will help with the potty training. He will have to whine or bark to get you to let him out and he will begin to associate letting you know he has to pee or poo with actually being able to go pee or poo.