Hi,
What other symptoms do you have apart from headache? Do you have any neurological deficits, fever, vomiting, seizures? Raised intracranial pressure is usually and emergency and can be caused by head injury, subdural hematoma, meningitis, encephalitis, brain hemorrhage, rupture of brain aneurysm and stroke. Did you try OTC pain medications for your headache? I think is is too early to conclude that your headache is due to raised ICP.
Without an MRI, spinal tap - how does he know you have high CSF pressure? Did he say anything after looking in your eyes with a bright light? You can look up Chiari, Benign Intercranial hypertensive ect.. It will get you to symptoms and such but are you sure you have this? You are right if the pressure is too high a spinal tap is dangerous, wait for the MRI. Give some symptoms and someone can answer some questions. For now you can sleep with your head elevated. Do you have pain meds? If it gets too bad go to the ER. Don't be too scared yet.