I am sorry to hear things are not working out too well with the topical medication. I googled Ketoconazole and looked at a couple of articles I have to say I was not impressed with some of the side effects. Usually ringworm is brought on to some degree in kittens and old cats due to the immune system being compromised. Are the cats getting a good quality wet food? Raw feeding would be great but that's another story. Previous medications or vaccinations also have a tendency to compromise immune system, or maybe the kitten had the problem before you got her.
As far as the milk Thistle capsules go, I haven't had any experience with them. A person would have to know what's in them other than the milk Thistle and is the capsule able to be split into small enough servings, because if you can't make the serving small enough it will have a tendency to tax the liver even more. The cats liver is very delicate and if you're not careful you could upset it's ability to metabolize what's going on in its environment even more.
I think if I was in your place I would be putting my faith in the colloidal silver since the Ketoconazole seems to be causing such a problem. How often are you applying the colloidal silver? I think if it was me I'd be looking at at least half a dozen times a day if not more. I am enclosing a website that has a decent article on treating ringworm, and maybe there's something in that website that would be of use to you in treating the fungus. And no doubt Sandy will have some ideas on treating the liver as well.
Hopefully there's something in here of value to you. I wish I was able to do more. I'll be watching for updates the best of luck.