I got Storm(male siberian husky) at 7 months old and he seemed potty trained within a couple months. I mean, at that point there was no accidents and he was awesome about going outside. Well, we moved beginning of August and he was still good for a month, but then he suddenly started peeing and pooping inside, no…
Try potty training him again and pay attention to him.
It may have something to do with the new dog because it could be that there is something he is afraid of if he goes to the bathroom outside. You should watch how both the dogs act together. If you see that they don’t like each other. You might have to take them out separately.
but don’t give up
if none of that works go to the doctor just in case he has a problem with his system.