My vet advises that you should give antibiotics for a minimum of 5 days (7 days for more severe cases), even if symptoms clear up before then, and you should discard any eggs laid during the treatment period and for 10 - 14 days after treatment is finished.
If you only have one sick bird then I would avoid treating the whole flock for 2 reasons:
1) you will have to throw ALL your eggs for three weeks
2) Giving birds antibiotics unnecessarily will not only kill good bacteria in their gut, it will leave them open to developing antibiotic resistance, which could mean that if they fall ill in the future it will be harder to find an effective antibiotic to treat them.
When I have one sick bird I weigh it, work out the daily dosage of antibiotic per kg, measure that out and mix it into a small amount of a treat (white rice, sweetcorn, bread...) I then separate the bird and feed the treat before putting it back into the flock. It's a bit more hassle, but better for all your birds in the long run. You also guarantee that the sick bird is getting a full dose of medicine - when you add it to the water you can never be certain exactly how much each individual bird is drinking, so you have no guarantee that they get the full dose every day.
If you need help calculating the dosage then please post the (approximate) weight of your bird, and confirm if it is indeed Tylan 200 liquid you got (the number indicates the strength, and is therefore essential in calculating the dosage). We can then help you work out how much to give your bird each day;
Best of luck.