Thanks for the additional information. I really appreciate it.
It's hard to say why she's having such a break in house-training. The fact that it seems to come and go makes me wonder if it's not some kind of anxiety causing her to behave this way....since she hasn't been with you long, it's not hard to imagine that the anxiety of moving into a new place could be it.
If she were mine, I'd start with an over-the-counter product to help with any anxiety she may be having:
Melantonin is an over-the-counter drug that can be used to treat some anxiety issues in dogs. The dose you would give would be up to 3 mg given orally whenever necessary up to every 8 hours. More information can be found here:
http://www.petplace.com/drug-library/melatonin-melatonex/page1.aspx , which includes risks, warning signs to watch out for and other bits of useful information.
Try a DAP collar. These are collars that are impregnated with a man-made version of the dog appeasing pheromone, which is a pheromone that nursing bitches give off to their pups to help them feel calm and secure. It's something that humans can't smell, but it has an amazing effect on dogs with anxiety and other issues. Although you can find them at your vet's office..you can also find them online at places like Amazon.com and Ebay for much cheaper. Just make sure they're DAP brand, as they seem to work better than some other versions.
Hopefully by using the collar, it'll change her mindset just enough so that she 'gets it' and stops making messes in your house.
I hope this helps.