That's worrisome.
No idea if this might apply, but DS used to wake up itching in the middle of the night. Terrible itching, and we'd do middle of the night back scratching sessions, benadryl, baths, you name it. He would slap his arm or leg, because sometimes that would help the itch. It *was* an allergy, but took us forever to figure it out. We knew he was anaphylactic to a lot of foods, so we avoided those. But after years of this agony, a new allergist did some testing and found four more IgE mediated allergies. We did elimination challenges, to see if it made any difference, and sure enough - wheat and dairy were significant. Less itching, less eczema, less asthma without those two. (The other 2 foods made no difference, thankfully.) ...No more midnight back scratching.
Not saying this is what's going on with your DD. But maybe it helps to know that other kids have that kind of severe itching, too.