third-fourth lateral ventricle

For several years now (33 y/o male), i have been experiencing an uncomfortable feeling, mostly unpredictable so far, in the back center of my neck.  Let me describe:  1) it begins at the mid-base of my neck and travels up towards the base of my skull.  2) it feels like some liquid like sensation, crawling slowly up, usually around 3 seconds or so, spaced about 30-60 seconds apart.  3)  I can hear it within, the sound is exactly like what ice sounds like when put into water.  not a crackling, but a fizzing sound and sensation.  4)  it is mostly noticable when i am sitting or lying down, and as i am sitting right now without the sensation, i can say it is very random, sometimes a few days in a row for an hour here, 15 minutes there, what have you, then nothing for a week (i have never strictly noted the occurances).  5)  It is not painful, just uncomfortable. I have no discomfort anywhere else when it happens, like a headache or neck strain for instance.  

      I had asked a physician once what he thought it may be, (he had no knowledge of my bipolar-II condition) and he quickly riddled to me that it was the symptom of a migraine headache, that i should take some ibuprofen, tylenol etc.  I accepted that as a sufficient cause, until recent while reading a short study about bipolar patients and how a finding concluded a 17% increased size in the ventricals in the lower brain of these patients compared to those without a bipolar condition, which honestly i really don't know what that means, but have an uneducated guess which has prompted my curiosity.  With some googling and research i am sure i can re-locate the study as i did read it online.  

     Does anyone out there recognize what i describe? Have any input or personal experience?  Let me add that this problem has occurred while both on and off prescribe medications.  Also it is hard for me to determine if the otc pain relievers are doing the trick because it tends not to last to long in the first place.

     I am not a worry-wort by any means, just want to be sure i am not letting what may be a severe problem go untreated.  The more i read about this stuff, the less i comprehend, with brain fluids and chofoid this and that.

     Thanx