Should I take my dog to the vets?

My dog is in her phantom pregnancy, she has had them before but she is acting loads different! She is very low and seems depressed, she is not very alert and refuses to go outside unless for a walk, even then she doesn't run around as much, and she is a spaniel who is 4 years old. She is doing the normal characteristic of pretending her toy duck is a puppy but not as much as usual, all she wants to do is lie down, she doesnt even wag her tail as much when I stroke her!! Should I take her to the vets or not?? Help me please, I'm really worried!!!!