What Causes Itchy Scalp?

Hello, I have a problem with my Hair. Im 14, & I think its a Hormone Problem. It itches alot whenever I do something to raise my body temperature, Such as Running, or even on a Hot day. I also get little bits of hair that fall out when I apply little pressure (Pulling at it/sliding my fingers through) my hair. I do not have Lice or Fleas etc. My scalp isnt sensitive, and I do use Natural Shampoo to wash with regulary (2 times a day) but ive stopped using it, as it did not help with anything. I am also a Type 1 Diabectic, so what could be the Problem?