do some research on cocci and see if the symptoms match what you read. but beware many fowl diseases have similar symptoms. sulmet and corrid will help with cocci.
apple cider vinegar is a good natural preventative measure. but if you have a full blown case of cocci, it wont help.
some will get it, and still survive, but it takes such a toll on them, that they will never be much. a sure sign of cocci is bloody manure, but not all strains of cocci causes blood.