The sulpher lime dip really works, but it stinks, and I mean stinks bad. I went through a ringworm infection last Nov and Dec after I adopted a kitten for an animal shelter here in GA. The stink is so bad, in fact, that after treating my pets the night before, showering and shampooing my hair that evening, and again the next morning, I could still smell it in my hair all day at work. My big cat had reacted negatively when I tried to dip him and got the dip all over my bathroom and me, and remarkably little on him.
Here are a couple good sites I went to, the second one addresses ringworm in the foster home:
Dermatophyte Treatment in a Nutshell | Dane County Humane Society: Helping People Help Animals and
Information Sheet - Ringworm (Dermatophytosis)
You absolutely deserve a medal for taking Chance, your heart is so good, and the shelter was very kind to hold him long enough to get him into rescue, most would have euthanized. Ringworm is just awful in a shelter environment. I really applaud you for your big heart and willingness to work to help this dog. Not many people would be willing to go through this. I can't wait to see Chance cured and a happy little dog. Bless you.