Try to get probiotics specific made for pigeons. You can give while he is on antibiotics and for a couple of days after you have finished the course. Do the acv twice a week.
Rather get terramycin eye ointment to use on the eye. Hopefully the eye can be saved.
Squeaking when you touch him, he is a youngster so probably has not learned to eat by himself. Get small seeds of all shapes and sizes, red sorghum is easy for them to pick up and swallow.
What country are you from?