My dog who was already potty trained is suddenly pooping and peeing in the house. How can I re-train him?

My dog Pickles, who is a year old now was potty trained like a pro. I could leave him out all day and he would never go in the house. Then, I went on a two week vacation where I left him with a girlfriend and ever since he has gotten back, he no longer is potty trained. I started crating him again, but I don’t know how to get him to stop this bad behavior. Today I crated him…came home, took him for an hour walk where he pooped and peed, and then this evening he pooped and peed again on my roomates bed (yikes). Any advice?