I had a spinal tap at Charing Cross hospital a week before lockdown started. Hardly felt a thing during procedure itself and was ok afterwards to begin with – made sure I lay flat for as long as possible and stayed in London that night. Next morning had to travel home on train for a couple of hours and was in agony by the time I got back – bad headache and sore back.
For a few days after that I got a really bad headache if I was up and about for long. Greatly relieved by lying down totally flat – as in not even propped up enough to be able to read or watch tv 🙄.
Back felt bruised but not unbearable.
I think the key is keeping flat as much as possible for as long as possible for those first few days.
Wishing you the best of luck!