Welcome to Health Care Magic
Relax. No need to worry -
The doctor would not have allowed you go home, if there was a serious problem...
Normal scan is very much reassuring indeed.
Both CT & MRI
Headache after lumbar puncture
is well known and has scientific explanation.
Take bed rest
/ drink plenty of fluids / use simple paracetamol
If the headache persists, see your doctor again
Wishing speedy recovery