to be honest if I have anything ailing 9 times out of 10 it's canker , but I ring the vets book an appointment same day and off I go , only a few miles to Northern Hygiene , I'd rather test and treat straight away for the ailment the bird has rather than treat blind as if you get it wrong you can give the ailment a helping hand to go unchecked at the detriment to the birds health , I look on Chevita for symptoms but my vet knows best , and I know better than to treat for the wrong ailment but nice to get an idea of what your birds are facing or the symptoms of the ailment as the quicker you recognise something is wrong you can act quicker to resolve it I see illness in a flock as a weakness but birds do ail , I generally find 9 times out of 10 if not canker they don't usually pull back and sometimes better to remove the weakest link , your loft is only as strong health wise as your weakest bird . Every garden grows weeds it's your job to remove them