thank you for writing in healthcare magic forum.
you need not to worry at all as its eruption phase for primary (milk) teeth .
it is the ginival (gum) flap overlying the erupting tooth.
mild swelling in that area can be there.
sometimes it is associated with mild fever
do warm saline rinses after every meal , assure your daughter that it is just a process of teeth erupting.
if symptoms get sever do visit a pedodontist.
if any doubt , feel free to write us back.