#1: DON'T RUB HIS NOSE IN IT!
I know that is an old remedy but it doesn't work. He can't help it and rubbing his nose in it only confuses him. Oscar hasn't "decided" to start peeing in the house. He doesn't think like we humans do so we can't project our behaviors onto him.
Is the length of time Oscar is left in the house longer than before?
Is Oscar crate trained?
Have you taken him to the vet to see if he's suddenly developed a urinary problem?
Maybe the "rubbing the nose in it, the cold shoulder, and other disciplines" is only making it worse. Try to see it from Oscar's point of view.
At the least, try crate training him for the time you are away. Do it gradually, positively, go on the internet for crate training ideas. It is not a punishment, but a method that dogs are comfortable with and can enhance your time with Oscar.
ITA with Anita!!! NEVER RUB HIS NOSE IN HIS URINE. This is a definite no, no.
Because it is done after the fact, he has NO idea why you are doing it. It definitely does not work and just makes him frightened of you. Has he been neutered?
There has to be something that has recently changed for him, either in his environment or medically. Since it’s only been in the last two weeks, it’s quite possible it is a UTI (urinary tract infection) and he needs to see his vet ASAP. It also could be stones in his bladder or kidneys. If he doesn’t have a UTI, then it is probably behavior and I suggest you contact a certified pet behaviorist and have them help you re-train him. I also agree with Anita’s suggestion of crate training AFTER a vet visit.
Please, please have him checked by his vet. You will feel very guilty if you have been punishing him for something he could not help.