I don't know how long you had her penned up by herself (if you did) but if she was ill, and unable to dust herself for a period of time, the lice/mites would get worse, of course. That can be a problem with sick birds. You can get some Diatomaceous Earth from the feed store, and dust them yourself once in a while, if you have to confine any more. I think that's safest, as long as they don't breathe it, but some people use Frontline spray or drops on their birds too, or Seven Dust. Just not sure how that stuff affects the eggs in the long run, if the bird does recover enough to start laying again.
) I try not to use any chemicals on the birds (or on my property for that matter) because they are such sensitive animals. 
