Personally I've had young bird sickness the last 10 or more years. In my opinion if your having to treat with an antibiotic to over come young bird sickness, you have a bigger problem then young bird sickness. Young bird sickness can be resolved in 3 days, and a difference in the birds can be seen in 48 hours. Many suggest small seeds, in my opinion, the first day no feed then a diet of 100% pellet should be fed, as any pigeon that is vomiting will vomit only 'mash' enabling no other pigeon to pick up the vomited feed. Hence controlling other birds being contaminated. In the drinker should be an electrolyte, glucose mixture. They also need plenty of rest. After 3 days let them out and offer them a bath. How they exercise and if they take a bath will gauge the birds health. Unhealthy birds will not bathe. IF and only IF they haven't shown any sign of improvement or full recovery, a secondary infection would have taken hold of your birds, And alternative treatment would need to be seeked. No grit or minerals are offered to the birds during any of this period