Anxiety and fear
Doctor Answers (1) on Anxiety and fear
What you are expericing could very well be a manifestation of an anxiety disorder. Anxiety beyond a certain threshold does show bodily symptoms, like palpitations, sweating, tremulousness, dizziness, chest pain. In severe cases it can cause a feeling of losing control, of being detatched from the world, and a feeling of impending doom.
The feelings of something crawling inside in your brain could aslo be a somatic manifestation of depression, or something even more sinister.
I therefore strongly recommend you to seek a Psychiatric consultation at the earliest. In most likelihood, it might be anxiety that is causing it, but do not ignore and delay seeking treatment.