I hope she gets better. I don't have any experience with canker to give any more advice. I doubt if the acidified copper sulfate would hurt, but just use it at 1/4 tsp per gallon of water for 3 days once a month.
How much does your chicken weigh? The dosage is roughly 25 mg per pound of weight (27.5mg exactly) given twice a day. Many sources just say 250 mg daily for 5 days, but a more specific dosage should be used. . I would probably reduce the dosage for her size since she looks small, and give it...
Hopefully Casportpony will see this and contact you. You can also PM her. Here is a link for pages of canker threads that you may want to check out: https://www.backyardchickens.com/newsearch?search=canker
Here it is for about a dollar per tablet with free shipping: http://www.amazon.com/Fish-Fish-Zole-250mg-30-Count/dp/B014V9RCYM
For canker (trichamoniasis) a solution of acidified copper sulfate 1/4 tsp per gallon of water can used for 3 days per month to help prevent it in other birds. Don't...
Canker may be the cause of the illness. I have heard that it also smells bad. If that is what is wrong, metronidazole (Fish Zole, Flagyl) is the best drug to treat it. Here is some info about canker (trichomoniasis:)
http://www.thepoultrysite.com/diseaseinfo/154/trichomoniasis-canker-frounce/...