Sick Chicken

One of my hens has a pale, slightly swollen crusty comb and a small bald patch at the front of her neck where her new winter feathers don't seem to have grown back.  Any ideas what may be up with her?

Not sure what the bald patch might be but I'd echo checking for mites etc.
Also might be worth just spraying a bit of antiseptic spray on the area.
When one of mine had a blackish tinge to her comb I put garlic in the drinking water and it seemed to clear up. I think garlic has mild antibiotic and antifungal properties. Could have been coincidence of course!