11 Month Old Pup isnt her self

Question
Recently our 11 month old American Staffordshire/German Shepard mix has basically lost interest in most things, We also have a 1 year old German Shepard/Shar-Pei mix who tears up the house, but the 11 month old , will play and torment the other dog for a while, then crawls up in our bed and goes to sleep, she refuses to eat, and are curious as to why she's going through this phase. she's a happy normal healthy puppy that just looks like she's going through a sudden bout of depression. Any input would be gladly appreciated

Answer
I would take her to the vet.  Although dogs can become depressed just like people, if there has been no change within the household (such as the loss of a family member or pet) I would be more inclined to believe that it is something physical.  If she is not current on her vaccinations that increases the likelihood.  The lack of appetite is what I find really concerning.  It could be something as simple as an upset stomach, but it's better to be safe than sorry.  I hope she gets better.

Amanda