I don't know what happened to me

I don't know whether to call this a meditation experience, a near death experience or a Lucid dream experience! But I decided to meditate before school so I layed in my bed and I relaxed all the joints in my body! (I was doing this while listening to a 435 music I got from YouTube) but then something happened! I don't know what happened but I started spitting and mucus/something came out my mouth and it was almost like I was having a seizer, my eyes were closed so everything was black but I got scared so I went back into reality and for 15 secs I was okay and then it happened again only stronger though as if I was trying to get sucked into something different! And then I managed to get myself back to reality and then it happened again! But not as strong as the second time! I don't understand this can someone explain if this was all in my head or if this was happening to my physical body because I just don't know! I remember using my finger and trying to press onto my thigh and it was as if my body was going numb! What happened to me?