They can be uncomfortable but are rarely very painful. They're a very frequent way of checking for intracranial problems. The lumbar puncture (as they're often called) will give your doctors a better idea about the source of your problem and most likely lead them to a good way to treat it.
Best wishes and try to relax, knowing that this problem is out of your hands for now.
DX: NDPH (2003-present), CRPS (1998-?) Abdominal Migraine (2010-present)
RX: Lamictal, Indomethacin, Propranolol, Provigil, Viibyrd, Oxycontin, Clonazepam, Zyprexa, Melatonin, Magnesium, Boswellia Serrata extract (Boswellic acid)
CPAP for mild sleep apnea