It feels like a bug in my scalp crawling why?

Paresthesia. Chronic paresthesia or intermittent paresthesia over a long period of time is generally a sign of a neurological disease or traumatic nerve damage. Paresthesia usually arises from nerve damage due to infection, inflammation, trauma, or other abnormal process. Paresthesia is rarely due to life-threatening disorders, but it does occur as a result of stroke and tumors.