I think I know what you're describing. The fact that I have heard this water-like or blood-like squirt running up from the back of your neck to your back of your skull. I feel like it is the best feeling for me (at least for a second to 4 seconds max). I feel like I'm relieved from my stress. I don't feel physical pain. I am afraid to ask my doctor about it as it may sound ridiculous. I have anxiety disorder, whenever that squirt of fluid go, I feel no worries. This doesn't happen a lot, I would say I get it random time such as once it goes, the next one could be a month later and then two weeks after that and so on. Usually happens when I lay down or lay either sides (left or right) or on my belly with my arms supporting my top body. All in all, it's the greatest feeling and no pain for me.