Sun-Sensitizing Drugs: See page 2.
It could just be a concern about sun stroke or heat exhaustion or overall fatigue.
Or an auto immune disorder.
Wow, that was very informative.
It might appear that some antibiotic or possibly even some cancer medications might be the reason she is hiding from the sun.
Not sure .. they mentioned things like Lupus, cancer, and a bunch of other drugs I’ve never heard about.
If you know some medical person .. maybe they can look at the info at MedicineNet.com and get more information that I did.