I would try the Benadryl (diphenhydramine) 1/2 a children's dose just in case. Here are a couple of threads that looked like coryza or fowl cholera, but turned out to be tick bites:
https://www.backyardchickens.com/t/950184/bulge-below-earlobe
https://www.backyardchickens.com/t/939516/hen-with-swollen-wattles-and-neck
https://www.backyardchickens.com/t/950184/bulge-below-earlobe
https://www.backyardchickens.com/t/939516/hen-with-swollen-wattles-and-neck