Here is a post from MedHelp that may help you. You may have to use the Ketoconazole shampoo for a long time ( such as 6 weeks for it to work). Some fungi are resistant to it so you may want to try Terbinafine shampoo or pills. But I would read some of the posts below. They may be helpful.
Hope this helps,
I think you can disregard the last post. It doesn't work that well. Another thought is you could have Ring worm of the scalp or hair shaft. Griseofulvin or Terbinafine are the treatments for this not Ketoconazole. Except that you can use ketoconazole for a shampoo in addition to the pills. This is provided your liver is healthy. They may do a blood test to check your liver enzymes. So you need oral Griseofulvin or Terbinafine pills (Lamisil). So I would see another dermatologist as that one doesn't seem to be up to date. They can do a culture and see what type it is and confirm that it is a fungus too. They can also add the shampoo. You may also have a secondary infection with a bacteria that may be causing the smell. So you may need an antibiotic in addition to the anti-fungal treatment to get rid of this. They should be able to tell by looking at it. If you have children or pets they can transmit it to you. So they may need treatment as well, I'm not sure of treatment for them. Don't share towels and personal items. You may have to throw out or bleach hats, combs, brushes, and linen (towels , sheets, etc) as you go.
Thank you so much for your advice it is very much appreciated. I will definitely try a different dermatologist and see if either the Griseofulvin can help.