my baby boy just turned 9 months last week and he was also sick with fever, runny nose and cough. his usual milk intake before sickness was 700-800ml a day and it dropped to 200ml a day at the lowest point. his lunch cereal and dinner porridge was taken ok.
since 2 days ago, he recovered with still a slight runny nose but not much phlegm anymore, his milk intake comes back to 720 today.
the phlegm is making him breathless while drinking milk, so he rejects. if you can be patient for another 1-2 days, he should be back to normal. if not, try spoon feeding him.