@ Waysidedesign - Personally, I used the suppositories, cut in thirds, but others here have used the cream and had success. The only reason I used the suppositories instead of the cream was they had fewer ingredients and seemed safer to me. No sense giving a sick hen a bunch of extra chemical junk she doesn't need mixed in with her medicine, right? That was my reasoning, but like I said others have used the cream and seen success.
As far as the yogurt goes, in my opinion if she will eat on her own that is best. All of my girls love yogurt and will eat it out of a bowl or even eat a blob of it right off the floor if it happens to spill. In my experience with my own sick hen, she was already so sick that she would not eat on her own, so I had to feed her with a syringe.
If your girl is still eating on her own and acting fairly normal, I would wait and see if the ACV and yogurt helps before I tried medication. I believe that medicine should only be given after all natural options have been exhausted. If your hen doesn't perk up in a day or two try giving her one third of a suppository twice a day until the suppositories are all gone.
This is only MY opinion, you should do what you feel is best for your situation.
Good Luck!