The acidified copper sulfate can be found online at Jefferspet, and is more of a preventative. Fish Zole is available online in 250 mg tablets, and you can split them in half, giving 125mg in the am, and 125 mg in the pm to improve the treatment. It helps to get the gunk off, and use some iodine on the site. From what I have read canker can grow to a size that can block the throat. Do you have a regular vet who might be willing to test the tissue or culture it? That might save you from unnecessary treatment, and expense. I noticed that the sore looks like a crater. I haven't treated canker, so am not an expert on treatment. Many people cull birds with canker, since it may make carriers of a flock. So it would be good to know for sure if it is canker. Another BYC member Casportpony, has treated wet fowl pox that has looked similar. You can PM her to look at your thread. Let us know what happens.
