Princess just went through that last week and is still on meds. She slept ALL DAY! She is 19wks. I went crazy too! I was so worried, I didnt know if she was going to make it. I thought it had something to do with a fall she had, but the vet said it was not. They put her on Clavamox and butophanol (not spelled right). Both of those seem to be helping her now. The 3rd day on the meds and she was bouncing around again! It'll be ok, just go to vet again and let them treat her and put you at ease! Keep us posted