There are many causes for hair loss. One is Androgenetic Alopecia which is genetic hair loss. But you said that baldness does not run in your family so you can pretty much scratch that off your list.
Another form of hair loss is Telogen Effluvium also known as diffuse hair loss. Basically you lose a lot of hair in a very short time and results from chemotherapy, high fevers, stress, and severe illnesses. But since you just have a small patch missing you can scratch this one off your list too
Then there is Alopecia Areata which is a sudden loss of hair due to an autoimmune disease. Your hair follicles are "attacked" by your own immune system. I don't believe scientists have discovered why this happens but the condition usually goes away on its own without medication.
These final three types of hair loss could very well relate to your situation:
Traction Alopecia occurs when your brush your hair vigorously or wear a tight ponytail.
Medication Related Hair Loss can result from certain medicines such as
Accutane.Diet Related Hair Loss which is temporary and results from poor eating habits and a lack of sufficient amounts of minerals, vitamins, and/or iron.
If you don't see re-growth within a few weeks, however, I might suggest you talk to a medical professional just to make sure that the baldness isn't an underlying symptom of something major.
in June of 2006 (unexpectedly). As a result of all that nutritional assault, I lost probably 70% of my hair (Literally).
I went to a dermatologist and he said not to worry. In fact new hair was already growing back. It took several months but the problem resolved itself.
