Ask him to reduce time spent on screens like mobile phones and laptops. Use blue light filter or night mode on phone if using in excess. Visit an eye specialist to check for dry eyes and refraction. Doctor can prescribe drops for dry eyes caused by excessive screen use. For ligament injury, ask him to wear a orthopedic support or visit ortho specialist.

I would advise you to have his eye sight properly evaluated and to minimize the amount of time spent on the phone, laptop, tv, etc. If the headache persists I would advise you to visit the neurologist so that you can be examined and undergo the necessary investigations to find the underlying cause and have it treated accordingly. As for the ligament injury he should follow up with an orthopedist.