physiobob - I see, thanks
nmarman - thanks a lot for potential causes. Nope, I don't have fasciculations of my tongue and, truth be told, over the period of last several days I'm more and more sure the fasciculations are just a symptom of my anxiety - I'm feeling better and better now every day, not thinking about each of my symptoms all the time and the fasciculations are practically nonexistent in the periods when I'm calm while they happen almost immediately when I start thinking about them (even if it's just some "Wow, I haven't had any today! That's great" and then bam - fasciculations in my arm, leg, back, lip, you name it).
And as for the initial question - strange thing as the headaches just... vanished. One afternoon they just stopped happening - they didn't become less severe, just went from "full blown mode" to "no headaches at all". I tried each and every position that used to cause the pain and there still isn't any pain involved at all. I still feel (a lot less but still) pressure in my head and sometimed in my nose area when lying/looking down for some time but there's no pain involved whatsoever.
How could it have disappeared just like that? I didn't change anything in my position. I mean - I stopped sitting on my wallet for several hours a day, keeping it in my suitcase instead but oh well - could such little change for two days cause such a tremendous improvement (or even causing them to vanish) in my symptoms?