Scary feeling when Masturbating?

I 17 year old male. And I have been masturbating for years now. But today something really strange happened. I tried a new technique I found online it involved o shaped fingers and light grazing the glands rim. And it felt really good like my breathing got faster and I did it for probably 20-50 secs and then all of a sudden I shot my c*m. And at the same time a hot rush feeling in my head by that I mean Brain that lasted a couple of seconds. I felt like i could p out if I let my self get into it but I didn't because it scared me. After that my hands where shaking for a minute and I felt hazy. Has the feeling in the head by head I mean Brain... ever happened to you? Was this just a really powerful ?? Or is there something wrong with me like a blot clot or hemorrhage or something in my head? Please I am really scared should I go to the doctor???