I got a sudden weird pain at left top of my head 10 hours ago. Not a headache, only pain in that one spot. No other symptoms. Now I have fear that is aneurysm and afraid to go to sleep. 21 y.o., no family history of aneurysm, no high blood pressure.

Head pain. If the head pain was sudden, Sharp and fleeting it may simply have been an irritable superficial scalp nerve. I would expect aneurysmal pain to be more lasting, throbbing and more intense. If you still have concerns, or have persistent symptoms, consult a neurologist for reassurance and peace of mind.