Weird head feeling been going on

Hi im a fourteen year old girl and ive been having alot of strange feelings lately so it all started back like four weeks ago when i had this weird feeling in my head that i cant explain but it only lasted about 2 seconds. Then i started to have pressure on my head but wasnt to worried about it untill a couple of days ago i started continuesly feeling the pulse in the side of my head to make sure i was still alive, i had read so much online about blood clots and tumors im not sure if its just scaring me or im over exadurating the pain in my head but there is a little pressure on the sides of my head it especially is effecting my sleep at night i cant fall asleep i also get very bad shaking in my legs and when i try to fall asleep i feel like if i dont keep moving i will die and had been a bit nausous and kept burping and farting then tonight i got some pressure on the back of my head but it felt like if youve ever kept your hair up tight to long, i baisically had myself convinced that i was gonna die and i dont want to go to the doctors because im scared its gonna turn into some horror story ive read and next thing you know ill have a brain tumor, but then i read online that alot of this is just stress but i dont seem to be stressed just obsessively stressed over this but i wasnt stressed before this stuff started happening iam just thourghly confused and scared this might kill me or i might have cancer or whatever