Look inside her beak for anything that could have been cut or injured. Bloody mucus in a bird showing signs of a respiratory disease is a sign of a virus called ILT or infectious larygotracheitis. They will typicially gasp, extend their necks, cough, and may sling bloody mucus around the coop. Here is a good link from The Poultry Site and blow that is an excerpt from The Merck Veterinary Manual:
http://www.thepoultrysite.com/diseaseinfo/83/infectious-laryngotracheitis-ilt/
ILT in Chickens
The Merck Veterinary Manual
Infectious laryngotracheitis (ILT) is an acute, highly contagious, herpesvirus infection of chickens and pheasants characterized by severe dyspnea, coughing, and rales. It can also be a subacute disease with nasal and ocular discharge, tracheitis, conjunctivitis, and mild rales. The disease is caused by
Gallid herpesvirus I, commonly known as infectious laryngotracheitis virus (ILTV). It has been reported from most areas of the USA in which poultry are intensively reared, as well as from many other countries.
Clinical Findings
In the acute form, gasping, coughing, rattling, and extension of the neck during inspiration are seen 5–12 days after natural exposure. Reduced productivity is a varying factor in laying flocks. Affected birds are anorectic and inactive. The mouth and beak may be bloodstained from the tracheal exudate. Mortality varies but may reach 50% in adults and is usually due to occlusion of the trachea by hemorrhage or exudate. Signs usually subside after ~2 wk, although some birds may show signs for longer periods. Strains of low virulence produce little or no mortality with mild respiratory signs and a slight decrease in egg production.
After recovery, birds remain carriers for life and become a source of infection for susceptible birds. The latent virus can be reactivated under stressful conditions. Infection also may be spread mechanically. Several epidemics have been traced to the transport of birds in contaminated crates, and the practice of litter spread in pastures is believed to be related to epidemics of the disease.