How to get my one year old to eat?

Chelsea

My son is 14 months old and barely eats since switching him formula to cows milk I have been stressed that he’s not getting all he needs he’s been staying between 19 & 20lbs but he will only take a few bites of food before he is shaking his head no the only thing he’ll eat more than a few of is crackers and that’s still if he’s in the mood. Any tips to get him to eat would be greatly appreciated