Is there an actual pus filled infection there or is it just red, swollen & sore?
If there is a true infection she should have it cleaned & wrapped by the vet. Depending on how it looks the vet may want to xray to rule out slivers/splinters
Is she licking it?
Dogs have an instinctive behaviour to lick wounds, even if it's just a sore muscle or sprained ligament they will wash the area that's hurt, sometimes to the point of irritating the area even more than before.
A properly fitted E-collar so she can't reach her food, vet-wrap or a sock on the foot will all help to stop her from direct contact with the area to allow for healing.
Dew claw removal is major amputation surgery at this point in her life, and I doubt it's necessary.
Avoid biting when a simple growl will do
The Spirit Lives As Long As Someone Who Lives Remembers You - Navaho Saying
Vindication ~ For all those pets who became sick or lost their lives from tainted pet food