I use the Tylan 50, but I inject it right into the sinus.  First I use a seperate needle to suck the gunk out of the sinus, then a CLEAN needle to inject in the Tylan (I used about .5 cc on a peachick about a month ago).  Usually one treatment takes care of it.  Otherwise, wait two days and treat again if necessary.  I don't inject into the muscle, it will cause permanent muscle damage.  There is a powdered form of Tylan that is labled for use on poultry (you add it to the water), the injectable is labled for cows and hogs only.  Most what I have read indicates that the powdered form doesn't work for this.  I hope your birds get over it soon, they just look so miserable when they get all swollen!