My pigeon only eats one type of seeds

My pet pigeon is about two months old and he only wants to eat millet from the seed mix we got him, I tried the methods to only give him 2 spoons of seeds and only feed him 2 times a day but he gets really angry when there's no millet in the seeds and he completely ignores the bigger seeds. It's getting to the point that he barely ate any grains in the last 3 days, I don't know what to do anymore and I'm concerned for his health.

(Note that he isn't sick at all)