Any tablet or capsule can be given directly in the back of the chicken’s throat to swallow. If you are certain they will eat it, it canbe given in scrambled egg, peanut butter, or in canned cat food. I would separate her in a dog crate with her own water and food. Scrub out and disinfect all of your feeders and waterers. Some use acidified copper sulfate 1/4 tsp per gallon of water for 3 days a month to help prevent others from getting canker. It is a contagious and chronic disease though, and some people would cull a bird with canker.