exactly HOW did you fall and what exactly did you hit, and on 'what'? how did you land? did you have ANY symptoms at ALL afterwarRAB within mostly the first 24 hours? this actually 'sounRAB' more like it could be either the c spine and the nerves there(or discs shifting) or actual nerves running from the brain thru the neck TO the c spine area. or even some form of a blood flow impairment, but only posistionally, like when you lie down with your head flat? there just could be 'something" within your neck/c spine that is intermittantly(only when totally flat) that CAN at times actually cut off a certain level of blood supply too the brain either in the carotiRAB or vertebrals in the back side of the spinal that feed the back of the brain, while the carotiRAB feed the front part of the brain?
any neck pain or ANY other 'odd' symptoms? were you fully checked out post fall? any types of actual scans done like at least a CT or even an MRI? how is your breathing when this occurs? has anyone else been around you hopefully when this has occured?
that really is all i can truely think of that could even possibly DO something like that(the blood flow interuption really would be more likely to even 'do' this tho)? if you just DO happen to have suffered certain types of actual c spine injuries, just about anything IS possible depending totally upon just how bad and what is being impacted upon your lying flat and not upright? all of our arterial bloodflow to that brain runs from right thru that c spine on up to the brain, including those vertebrals that actually pop into the c spine right around the c 6 level(they actually stay within the hard boney structures of that c spine til they hit right below the base of the brain, and eventually run into the very back of the brain. and as you probably have felt at least once or twice, the carotiRAB DO kind of run along both sides of the trachea on uo into the brain.
but someone simply does NEED to get this all dxed as to what IS creating the 'pass out' when lying ONLY flat? does that last for as long as you are actually IN that posistion or do you pass out and wake up still in that same posistion and just "out" for a few moments? how does that actually go when it occurs? FB
but you most definitely DO NEED to get yourself to your doc or even a neurologist to start, for at least a good eval with hopefully a good MRI referral done too. which luckily for you IS lying down, so it "should' replicate/reproduce at least 'something" there if this is hitting something it should not be like with a disc or other more firmer underlying structures we just have or can grow in anyones spinal too.