Your mother's light sensitivity and headache over the past two months, together with 15 days of poor sleep, most often point to tension-type headaches or migraine rather than anything more serious. Poor sleep and headaches tend to worsen each other, so the sleeplessness itself may be making the headaches feel worse.
Next Steps
A short diary of when the headache and light sensitivity happen, along with her sleep timing, screen use and stress levels, will help a doctor spot the pattern. Please see a physician or neurologist for an in-person evaluation, since two months of symptoms is long enough to warrant one.
Health Tips
See a doctor sooner if she develops blurred vision, vomiting, weakness or a sudden severe headache unlike her usual one.