6 month old won't drink his formula

Anyone else have issues my son was sick with a cold & at the same time I stopped mixing his bottles half formula half breast milk to all formula and he slowly will not eat his bottles ....they want him to have 24oz of milk.... and I'm lucky if I can get him 12oz he is eating babyfood....

so he does have like 2oz of rice or oatmeal and 2 oz of a fruit or veggies for breakfast lunch and dinner and in-between or before hand I try the bottle but he won't drink more than 3 to 4oz at a time.

Any suggestions??