My Son Is On Vacation In Tokyo, Japan. He Just

My son is on vacation in Tokyo, Japan. He just called and said his eye is bloodshot, red and itchy. He wears contacts. I told him to throw the ones he was wearing away, use warm or cool compresses, whichever felt the best. To hydrate his eye with his eye solution, leave his new contacts out until his eye feels better, and wear sunglasses. He says he is having trouble seeing out of one eye.
I suggested some non drowsy Benadryl, Aspirin or Ibuprofen for swelling or pain.
Is there anything else I should tell him. How will he know if it is an infection? He will not be home until Monday morning.