Electrohypersensitivity is a fake condition, its basically a placebo mental disorder, the person basically for some reason makes themselves believe that things like wifi, bluetooth, or cellphones signals make certain parts of their body hurt, it can range from the eyes, to ears or the head itself.
Rumors say its started from people who learn that things like phones emit slight radiation, and they link radiation to to hurting and somehow you end up with this.
OP, just dig up a bunch of proof that its a Placebo Disease and you'll be fine, if she actually does take you guys to court, you could probably do a counter and have her get a mental evaluation, to save any other business from this hell.