Obsessive-compulsive disorder is an anxiety disorder in which people have unwanted and repeated thoughts, feelings, ideas, sensations (obsessions)
, or behaviors that make them feel driven to do something (compulsions).
Often the person carries out the behaviors to get rid of the obsessive thoughts, but this only provides temporary relief. Not performing the obsessive rituals can cause great anxiety.
sensation - a general feeling of excitement
and heightened interest; "anticipation produced in me a sensation somewhere between hope and fear"