Non-emerg: tail bobbing when breathing - need to do something?

[Gypsylion]

Threehorses, you commented in a post about someone else's sick bird that tail bobbing was an indication of labored lower-body breathing.

Quote:
I have a 2-3 month old d'uccle pullet that always opens her mouth just slightly when breathing, and nearly always tail bobs as well. Does this indicate a big problem? Is it fixable? Where should I start?

Thanks!