Your baby boy has a serious eye infection. Yes, it hurts. You can see the pus, which is waxy and firm in chickens, starting to crowd around the eye.
You can take him to an avian vet to be treated or try to treat him yourself. First, you will need to express the pus from around his eye. Watch the video I've posted where a vet is treating a chicken with an infected eye. Then you will need to get some terramycin ointment and use it every day until the eye returns to normal.