The only way to be sure is to have the droppings tested,if you have to send them away they won't show canker because they will have died.Throat swab is the best idea if you know anyone local to you who has a microscope and will assist.Don't be frightened to put 0.5ml of domestos in a drinker (if you have nonifura mycin),this would clear any bacterial prodlems.For Cocci,boycox can be given any time as it is not absorbed by the gut and does not affect the birds digestive system.As for canker there are several good products on the market,if you use cider vinegar regular this may assist keeping most probs. away because of it's acid content.If you have problems getting the tests done,I find that if your birds are feeding young and are dirty feeders i treat for canker,if the droppings are dark green and geasy cocci.This is only what i have found over the years,but if pos DO NOT treat your birds without tests.My opinion only. Hope it helps.Lindsay C.
PS.What part of the Country do you come from.