Ive had Miley for 3 years but 2 out of those 3 years she's been an outside dog. But since I brought her to live with me and my boyfriend, which its been 3 months now she just peed twice in this last week, before that she's been THE BEST DOG EVER. Were usually away from home for up to 8 hours and we come home and take her out, but no mess when we arrive. Also she just got done with her heat, could that have anything to do with her randomly peeing?

Have you taken her to the vet yet for a checkup? That's the first thing to consider, something medical. And maybe get her spayed too. That way you will avoid the heartbreak of her earlier death after diseases that could have been avoided with a spay.