Chicken bald back

[Cozpip]

I have had a hen who's eggs have been getting progressively smaller and paler in colour over the last month. I noticed this week that her bottom was quite dirty and then today I found the poor girl had passed away in the run. Quite surprised she was outside and not in the Eglu too

I'm not sure if any of these things were related, but just wondered if any body had any ideas as to what may have caused it? I worm them regularly with vermex but am wondering if I should maybe get some antibiotics for the others n case it's an infection of some sort?

[Redwing]

It could be infection but I would start by worming the birds with Flubenvet which is the only licenced wormer for chickens. Vermex is not a wormer but does have a use as an intestinal cleanser and balancer