Don't want to drink milk

Good morning! Am a mother of 1 and 4 mos old baby boy and in 3 days now, he doesn't want to drink his milk. We tried to change his milk but he still refuse, also we tried to put the milk in a glass but still refuses to drink his milk. Though he eats a lot but I'm still worried. Any option or suggestion? Thank you in advance it will be a great help.