He might have scratched his cornea and that is VERY painful. I have no idea about using Visine or pink eye meds on a pet that are normally used for humans. Do you have an ER vet in your area? You should consider taking him in to be seen. You cannot see a scratched cornea with your bare eye, they need to put drops into the eye and look at it with a special light.
*If he is squinting and favoring that eye then he is in pain.
