Every time i run or get nervous, i start itching all around my scalp and my neck and my chest, it fells almost like ants are crawling on me. what isn?

Urticaria: One possibility is cholinergic urticaria. This is a form of hives that causes itching and is triggered by things like exercise, heat or cold. Usually there are red welts associated with the itching. Oral antihistamines such as Claritin (loratadine) or Allegra can help control this. If there is no visible rash, consult your physician or a dermatologist for evaluation and work up of your symptoms.

Common occurrence : Can be dryness of the skin but also sympathetic reaction causing hormones to increase with skin vasoconstriction and decrease flow to skin. Will improved with improved conditioning.