Bald spot on sideburns why?

A
45 yr old female with hair loss in one side burn and now the other.  I recommend seeing a dermatologist with
plenty of experience in hair or a hair transplant surgeon to examine your
skin/hair and possibly a biopsy.  You
should also have a microscopic evaluation along with some blood work.

The cause of hair loss may be traction alopecia because of high stress on hair or any kind of alopecia . you should go to  a dermatologist to find out reason .hair transplant may provide you a solution for that problem.