What Causes Patch Of Baldness On The Back Of Head?

There is patch of baldness which started appearing 4 months back and is now increasing its size rapidly. Its located at very unusual location for hair loss. On the back of head 3cm below the round cyclone type circle of hair which most males have on the back of their head, The patch is surrounded by heavy hair. It looks like some razor is used to make a hole between hairs. My doctor prescribed me Minokem-n 5% to be applied twice a day , also tenovate m to applied 2hours before bed. Also a tablet Folibuild to be taken once a day. But the patch is still increasing it size. From 1cm diameter to 2 cm now. In just 1.5 months. What should I do?