Phantom pregnancy in bitch

Hi all,
Just after some advice or information. My 4 year old bitch had her most recent season sometime in mid-summer (I forget exactly when. July, maybe)
Last few days she has been a bit hyper and has started today to whine constantly (she's usually quiet) and is obsessively carrying soft toys around, has also been doing a bit of nesting and looks as if her mammaries may be swelling. I'm certain she isn't actually pregnant, so I'm assuming it's a phantom.
Is there any advice on how to make life easier for her (and me!) and how long is it likely to last?