they can get their nostrils plugged and cause minor eye problems, sometimes crusty eyes. this could also be the start of some respiratory infection.
as long as she is eating and drinking ok, and no other birds show symptoms your probably fine. I would isolate her from the rest just in case. if symptoms get worse, you may have to start antibiotics.
I like to start with the most mellow treatment and work my way up. if she is eating and drinking I would add vet Rx to her water, and put some under her wing. if you have isolated her and have bedding, you can add a few drops to it too. this helps to open the sinuses. I use this a lot on sick birds because more oxygen promotes healing. if you cant get the vet Rx you might try some peppermint leaves or oil mixed lightly in her water.
if she is not eating, her weight is good, she is still active, use water soluble antibiotics for broad spectrum chicken respiratory infection.
if she is not eating, and this has been going on for more than 2 days, I would give her 1/4 cc tylan 200 for standard bred (or 1cc tylan 50).
if she is a bantam use 1/2 cc tylan 50. give in breast, push needle in, pull back just a little before giving injection. do this for 3 days.
I have heard of people doing sinus flushing on chickens, I never have done it and am not sure how to go about it.
keep me updated,
brian