hi msstess and welcome. this sounds very strange, all I can think of is these flea control products contain insecticides/pesticides and some can be very toxic to pets and humans both. frontline contains FIPRONIL which can cause 'over excitation' of the nervous system...could this be whats wrong???
if Gigi were over sensitive to this product perhaps its cause her nervous behavior to become even worse.
Did you use this on the carpet as well? could than sure be 'over exposure'...signs of fipronil poisioning are dizziness,agitation and seizures to name a few.
http://www.simplesteps.org/greenpaws-products#/h/+/+/623
I would give her another bath to get this all off her, although by now it would mostly have been absorbed into her system.....if you have it on the carpet I would shampoo with plain water...no chemicals of any kind.
are you sure it was fleas to begin with? did you just see the sores or did you actually see fleas??????
If Gigi doesn't show some return to her old behavior after this bath I would suggest you take her to a Vet, or at least phone one....to see if they think this could be a poisoning situation...sure hope not, please keep us posted and best of luck to poor Gigi.
you can also post this question to Medhelp's Vet expert and see what he thinks...
http://www.medhelp.org/forums/Animal-Health---General/show/112?controller=forums&action=show&id=112&camp=msc