Foul Smelling Head, Some Nasal Discharge

Today I noticed that my small frizzled cochin hen was gasping for air. I went to assist her and saw that her nostrils were clogged causing her to breath through her mouth in almost yawning motions. I immediately removed her from the flock and set her up in a pen alone in the front yard. She quickly stopped the "yawning" breathing and is back to breathing normally. Her nasal discharge has cleared up but her head smells SO BAD. I am very worried. I have since changed my clothes and washed my arm and checked the rest of the flock. Everyone else is completely fine. I put a healthy bird in the segregated pen with her but thy are not enjoying eachothers company and i fear now i cannot separate them. I figure if he gets ill too then it is contagious and i will have to cull. In the meantime is there ANYTHING else that could be causing my poor girl to smell so awfully? I have not introduced any new birds in a long time, or visted any other flocks in over two weeks, and even then i came home and changed my clothes and shoes and showered to be safe. I am at a loss as to what this could possibly be or how she could have gotten this way. Help?

Thank you. I have felt around her crop. It is squishy and i feel no hardness or lumps. The nasal discharge is dried up right now but she definitely had it earlier. She is showing no signs of facial swelling or discharge from the eyes. I am having a hard time pinpointing the cause of the odor though. She is so tiny that when i open her mouth i still smell the stink, but cant tell if its from her nos or her mouth...

well thats why i wrote no discharge from the eyes or facial swelling, those are teltale signs of coryza. Although the nasal leakage came back and i q-tipped it and the q-tip smells so that is where the odor is coming from. I guess it could be infectious bronchitis... in which case i am thoughroughly confused because I have not brought in or been around other birds in a long time

I know youre trying to help, im sorry i wasnt trying to come off unappreciated.....just totally confused. I have no clue how this could have possibly happened.

I do hope he makes it. If he is older I would suggest getting a de-wormer...i lost a hen once and she started off not walking, looking sleepy, not eating...It was on fourth of july weekend and everything was closed for three days :(