Housetraining our new puppy/NEED ADVICE

Hello All,we recently aquired an new11 week old Yorkshire terrier/toy Poodle mix.She started out doing pretty well not having many accidents in the house,but the last couple of days she seems to have regressed eliminating from both ends and from what we believe hiding the dirty deed as well.What can we due to curb this issue and what should we due to strenghten our proactive approach.