What Causes Pressure In Head?

i used to smoke weed alot, everyday,, and i was fine,, i loved it and would never get too high or anything. lately i have bad pressure in my head! its not like a head ache its more of an annoying pressure that sometimes almost feels like my head is going to explode or something and i feel like i just might die! i try to controle it and at first thought im juss not used to smoking weed again so i kept smoking but it never got better and now i just have constant pressure and im paranoid and always feel like im going to like die or something! im too scared to get a cat scan or an mri because im afraid they are going to tell me i have something really wrong with my brain! idk what to do about it! any suggestions!