Yep...i agree with everybody, check this with your vet. Mojo had a few bald spots on his head a few months ago, the hair just fell, it actually looked like the hair was plucked, the skin was clean without 1 single scratch. After taking Mojo to the vet, we found out it was a little irritation, he was on medication for 1 week.
The sooner you find out whats wrong the sooner this will stop