Tip of Finger Fungus

Good day,

I've been having a fungus on the tip of the middle finger for more than a year now. The condition looks like a white thick skin that cracks and peels off.  I went to my family doctor and he prescribed me Nystatin and Triamcilone Acetonide Cream.  The condition got better but it comes and goes.  Nonetheless, the spot where the fungus is does not go away.  Moreover, when I stop using the cream (because of irritation of the skin), it comes back.  I went to my doctor again and he prescribed me the same thing again.  When I asked him to send me to a dermatologist he told me that there was no need for that because what I have will not go away.  What should I do?  What do I have?Attached is a picture.