Urine trouble

We have a 6 year old male Schnauzer/Poodle/Wheaton Terrier mix. He was housebroken fairly well. Now, recently, he started peeing in the house again. He has never had a bowel movement inside since he was a puppy. We are unsure if it is a behavioral issue or a medical one. He normally pees in the same two places, but not these exclusively. Now, thinking about when this started, we realized that it started during the summer, when we had our cousin's dog (a female yellow lab who is a year younger or so) so it may be a behavioral but we are not sure. Any help or ideas? Do you think we need to see a vet? Is there any way to tell if it is a medical or behavioral issue?

Did you clean the areas with an enzyme cleaner (like Nature's Miracle)? If the smell is lingering it could encourage the dog to pee there again.

Have you ruled out any medical issues like bladder infections? That might be the first step.

Assuming no medical problems I would act as though I was starting the potty training process over again with him, then slowly give him more freedom as he becomes more trustworthy.

Our dog did that when there was major changes in our lives, I was working more and she was left alone, sleeping by herself, move, etc.

We had to make sure to use the spray to neutralize the odor and we don't let her drink after 5pm.