Pulse beat feel back for head. Of head?

Hello, Do we feel pulse in back of the head when kept on pillow? Due to vitamin deficiency Due to vertigo positional (when slept on right side) I did epleys maneuver and threw up twice. From 3rd day No vertigo but got rapid heart fluttering and pulse feeling back of head when head is kept on pillow. It's very disturbing during sleep time . Cardiologist  did all tests and ruled out heart problem, but gave beta blocker for tachycardia. Did MRI for neck and brain and found no abnormalities (attached) Vitamin b12 is 58 and vitamin D is 20. Very less. What could be the reason for feeling pulse back of head? Please tell me from your experience. I have visited numerous doctors evryone rulesout saying anxiety. That's not the case, I don't feel head pulse just because of anxiety. Even if I keep my head against pillow during day time without any stress or anxiety, I feel pulse and slight involuntary push movement.