I am glad to hear they are feeling somewhat better. Hopefully they will make a full recovery. After the antibiotics make sure you give them probiotics and a good vitamin and mineral supplement in their water or feed. I find water easier. I would do this on a regular schedule to keep their health up while carrying this disease. Maybe once a week. Also, try not to stress the chickens as that can cause relaspe.
As far as the eggs, every chicken is different, but keep in mind that the days are getting shorter and chickens naturally slow down on egg laying with the shorter days and usually come to a stop in the winter months.
As far as eating the eggs, I wouldn't. I'm surprised a vet said that. It seems to me that ingesting a small amout of an antibiotic would cause bacteria(should you pick some up) to develop immunity to that antibiotic and thus it would become ineffective for treatment. That is what is going on with the "superbugs" that are developing today. Antibiotic resistance because of antibiotic misuse. Of course, if Tylan is something that is not used in humans (I don't know), and never would be, I guess it wouldn't matter.