Well, first you should get him to go to a doctor and be comfortable with it. It's something adults have to do. Genital problems occur and it's better to have them treated than make them worse.

As for killing the yeast infection there are several natural infection fighters that you can get over the counter at health stores. Such as Colloidal Silver or Oregano Oil. The silver can be taken internally as well as applied externally. The oregano oil is only internal when dealing with the genitals, as that would burn badly. Any immune boosters would also help, but probably not strong enough to kill an infection quickly. Such as Vitamin C, Zinc, Astragalus.

Externally he could probably also apply creams sold in stores for female yeast infections. Since you're talking to your doctor, might as well throw that question out to make sure.

You and him should also take a probiotic. Probiotics are good bacteria that are beneficial in many ways, including killing and keeping bad bacteria in check. You can find supplements in health stores. Look for multi-strained, high count, enteric coated. Take higher doses for a couple weeks after antibiotic use or after killing or getting an infection. After that just take the normal dose.

Probiotics can also be purchased for vaginal insertion and this should greatly help with yeast infections. Yogurt contains probiotics and can be used externally for yeast infections, or even as a douche of sorts I've heard. Use plain organic yogurt. No reason to get flavored because you're not eating it, plus the sugar isn't good when dealing with infections.

So do you think you can get your husband to dip his penis in plain organic yogurt for a while?