Dogs do get constipated. I fed Wolfie pureed pumpkin when he was constipated. It did the trick. Is Liisi drinking enough water? Maybe she ate a rock? My dog Major used to do the same thing that you described Liisi doing and it was because he had eaten rocks and was having a hard time passing them. In any case, I would certainly call the vet for advise. I hope she's ok.
Chases Wolfgang Heinrich Von Ryan aka Wolfie born 12/20/09
Waiting for us at the bridge is Chases Chieftain aka Chiefy Left this earth and left a hole in our hearts July 2000