Weird itchy tingling sensation across my back scalp top of hands and my chest , feels really strange what is this no rash or anything goes away after around 30 seconds on and off for months?

Neurological: Abnormal sensations of warmth, cold, crawling, tingling or numbness can indicate a problem with the neurological conduction system. It would be wise to seek a thorough evaluation to determine if there is an underlying medical problem causing this. A primary care Dr can do the initial assessment, but a Neurologist may be necessary to pinpoint the problem.