6 month old refusing formula

Shianne • Beautiful little boy. 12/23/17 💙

My son turned 6 months June 23. He is refusing his formula the last week. I’ve been giving him as much as he’ll take but he’s eating 1/3 of what he typically eats.

I’ve tried giving it to him in a sippy cup and he’s super interested until he realizes what’s in it.

Has anyone else went through this? I know it’s a question for the doctor, but has anyone switched to cows milk at 6 months with no problems?