I need to treat my 17, 5-week old chicks for cocci. I pulled out my bottle of Corid - bought earlier this year, and expires in 2017 - and there is mold in the cap. Possibly some of the spores have dropped into the medication, too. Is it safe to use, or should I get a new bottle? Also, can I offer my chicks some plain yogurt while they're being treated for cocci?