If your general doctor has prescribed you Ketoconazole 200mg to use twice a day, you definitely have a yeast infection. That doesn't mean nothing can be done, most people here have a yeast infection that within their body. It might not be in every organ of your body, but maybe there is overgrowth in your gut, there really is no way to know.
I'd continue taking the ketoconazole prescribed by your doctor as well as go on a good candida diet, not a junk candida diet. Do that for at least 6 months and see how you feel. Just because the yeast is in your body doesn't mean it's the end of your life. If you worry about it more you will have worse symptoms.