Having pressure headaches and dizziness. occasional clogged nostril either one side or the other. im a hypochondriac so scared of brain tumor.

See a neurologist: More likely you have migraines. Tumors only uncommonly cause headaches. A ct scan head can allay your fears. Your neurologist will make proper diagnosis and manage your symptoms.

Could be many things: That could actually be a migraine prodrome. Alternatively, viral infections (flu, stomach cold, etc) can lead to aseptic meningitis - not life threatening, but painful headache +/- dizziness. Lastly, tension-type headaches often present that way. See your neurologist to make sure it isn't anything serious, and then get it taken care of. Good luck!