Here's a link to coryza incubation period and course times:
http://www.zoologix.com/avian/Datasheets/InfectiousCoryza.htm
Mycoplasma Gallisepticum (MG) :
http://www.agf.gov.bc.ca/ahc/poultry/MG.Infection.pdf
http://edis.ifas.ufl.edu/ps034
One of the telltale signs of Infectious Coryza is a foul odor about the head area. Also, it's possible that it could be Mycoplasma Gallisepticum (MG) or both diseases together. For both diseases; survivors will be carriers for life and will spread the disease(s) to healthy birds. I recommend...