[Liv1]

Hi! I've all of a sudden noticed everythings going wrong.. The feeling of my flock is odd! A few of my girls are not acting themselves, my light sussex is lethargic and sleeping a lot, she hasn't got a cough or any discharge, her feathers are fine, her vent looks fine. Any ideas what could be wrong with her?
There are a few who have a rattly cough, one has always had it - she has been wormed and antibiotic-ed but shes just kept it for the last few years, but the other girls they have discharge from their nostrils and really watery poo. Including a broody who has just hatched 5 chicks.. I've read it could be mycoplasma? How do I treat this?
The number of chickens has crept up on me and they all (31 - 27 since they have been ill because of broodies in seperate huts) live in one shed I think its about 8ft by 6, is this overcrowded? They all snuggle up at night so there is a good couple of ft spare on the perches, and there is a window been partly blocked up for ventilation. How many chickens should I be keeping in this much room?

[joyfull]

only a vet can diagnose if it is myco - so take one to a vet. If they confirm it is myco then you can never cure it but you can usually manage it. It can flare up in times of stress such as a moult, the introduction of new birds, any change of routine etc, the list is endless.
When it flares up they will need a broad spectrum antibiotic such as aureomycin, tylan and denegard, and you will need to treat them all. You will also need to throw away all the eggs whilst they are on the antibiotics and depending on the antibiotic possibly upto a month afterwards.