Painless pressure in head won't go away with painkillers? pressure in head can cause dizziness, drowsiness and anisocoria (unequal pupil size)?

Emergency: Without an actual examination, I cannot give specific medical advice on your particular health, but, signs of a life-threatening amount of pressure in the head (tumor/bleeding/mass as possible causes) would include drowsiness, change in pupils, change in mood/alertness. and sometimes other neurological symptoms incluing balance/dizziness or weakness or seizures.