It's so stressful when they scream while you are trying to feed them! Have you tried holding him in a different position on the right side? Like if you normally cradle hold him, have you tried the football hold?

I'm no expert, but I wonder if he has an issue with his neck? A lot of babies with neck issues start refusing one side. I only know this after years of taking my babies to a paediatric chiro LOL! I highly recommend taking your little man to one to get check over JIC. I see a fantastic one that I'm happy to forward on the details to you if you'd like. Just let me know

I hope thing improve for you both soon .