Coughing and sneezing

What antibiotic did you use? If it was a form of Oxytetracycline (like Duramycin, Terramycin, LA200, or Tetroxy HC-280), you should continue the antibiotics for seven days or so. If you stop antibiotics too soon, disease will often reappear. Of course, the antibiotics might also have just not completely cured the disease; they may have been too weak.

Tylan50 or Tylan200 are the best antibiotics to use for respiratory diseases. There is a water soluable form of Tylan, but you would have better luck with the injectable form. The dosage for Tylan50 is 1cc for a large fowl, .5ccs for a bantam, given for five days. For Tylan200, give .5 ccs for a large fowl, and .1-.3 ccs for a bantam, for 3-4 days.

If you have been using Tylan, I don't know what you should try next. It may be that you are dealing with a virus, or a virus/bacteria combination. You may have treated the bacterial part, but the virus might remain. Just keep your birds warm, well fed, and hydrated. Electrolytes and probiotics (don't give probiotics when giving antibiotics) are also good ideas.

Hope this helps!