my 3 red sex links have this on their combs.

[Featheredfan]

Any ideas what t this could be?

 

[Eggcessive]

Favus may be a possibility, from a fungal infection. Do all 3 look the same? Would another closer picture of one be possible? Miconozole is good for favus, but I am not sure about that being the problem.
Actually, it may even be an injury from a scrape, so I would investigate more.