If you mixed the tylosin in water for your sick birds to drink; it's ineffective administering in this manner. Sick birds rarely drink. If they do drink, they dont drink enough of the treated water to be effective, or they simply just dont drink.What do you think would have them sneezing, head shaking, and doing the neck gape thing? Do you think tylosin just wasn’t enough to kick a respiratory disease?
Injecting each chicken or administering antibiotics orally to each chicken is the only way you'll know that they were properly dosed. Most likely meds are given twice a day over a period of 5-7 days.
Antibiotics are ineffective if it's a viral respiratory disease, such as Infectious Bronchitis (IB.)