Hi. See my response to your other post.
I think you need to stop catastrophizing. An LP may not even be ordered/necessary. And even if it is (which happens less and less often), only 1 in 7 gets complications such as headache. Probably many fewer if done by a competent doc who uses flouroscopy. Many years ago I had an LP, waited the requisite amount of time, got up, drove home and resumed my life.
One in 7 may sound like a lot, but that also means for 6 in 7 it's a non-event. Don't borrow trouble.
I am probably going to have to get an LP. I'm even more freaked out after reading your posts above. Currently no symptoms other than fatigue, constipation, brain fog, and blurred vision when I only eat carbs... so I'll be pissed off if I get some freaking physical condition based on one of these docs tests!
I had some pretty serious neuropathic pain in my leg post-LP .. neuro said it wasn't related, but it took months to go away. Medication helped me cope until it finally disappeared.
I have also had sacral and radiating pain as you describe as part of ms.
Definitely call your neuro and/or doctor. Whether or not it's due to the LP or not, physiotherapy and acupuncture was what helped me in the end. It wasn't a quick fix .. but take heart because it may not be permanent.
I only had the headache - please call your doctor ASAP. That is not a typical reaction. It's possible they hit a nerve, but you should really be seen.