What could be cause of intermittent pressure that pulsates in the back of my head? no pain, just pressure which seems to pulsate or throb at times.

Exam: Never postpone an examination and r CT scanwith a pulsing sensation in your head- get checked or go to ER ASAP!

See a neurologist: These symptoms may represent a headache or other neurological condition. You should keep a log of the location, timing, duration, and intensity of these episodes and take the log with you to a neurologist. https://www.aan.com/Guidelines/Home/ByTopic?topicId=16