My 3 year old son is complaining of headache and eye sensitivity. There is no fever, no nasuae no vomiting no ear ache or severe sinus. There is no sign of a head injury or a concussion his pupils also dialates according to light exposure.

Early signs. This is often a very early sign of a viral illness. I would expect it to provide more symptoms within the next 12-24 hrs to become more apparent. He could certainly take Ibuprofen for the time being & put a cool compress on his forehead for comfort. The pattern does not suggest anything terrible at this point.