I haven't had much experience in fungal infections in cats, but when it comes to liver problems I have one whose liver was compromised 10 years ago and 3 or 4 times a year I have to do a liver cleanse. I have used several different manufacturers of Milk Thistle, but the best one I have found is turned out by a company called A. Vogel. I usually administer it 2 or 3 times a day. I usually mix 2 or 3 drops of Milk Thistle with 1 1/2 mL of water and administered with an eyedropper. The milk Thistle has a wee bit of a strong taste and it's really not appreciated by the cat but Missy has learned to persevere with this for treatment lasting from 10 to 14 days. If possible, add a little more water, it might make it go down easier. And I use distilled water.
I've used colloidal silver for years and have had generally good success with it both with the animals and myself. I've used it both internally and topically for burns, cuts, scrapes, and eye infections. If you're using it topically on the fungal infection I would be interested to know how it works because I haven't had a chance to use it for that application.
Here's the website of the company to give you an idea what I'm using. I hope this info will be of benefit to you.