What Causes A Strange Pressure In The Head?

hi ive been smoking weed for three years every day and never had any problems. but sometimes in the last few seshions i felt a strange pressure in my head that went away after like 3 to 5 hours. but the last time i smoked weed (06.28.2016) the pressure never went away. i stoped smoking weed, drinking alcohol, smoking cigarettes and drinking caffeine. i also started to do sports and drinking alot and eating healthy but nothing worked. this pressure scares me and made me feel sick i even had to throw up sometimes.