Ugh, I'm sorry..that sounds awful! I had a couple bad LP experiences, but can't imagine not being able to be fully medicated. I wonder if your blood pressure is higher because of the pain. I know it contributes to mine when IIH is acting up. Do you get any relief after they do the LP? It doesn't seem like they drain near enough. I usually had a closing pressure in the mid-teens or single digits, of course I think my pressure was only over 50 once.
A shunt seems like the next logical step. I was taking Diamox and Lasix before my LP shunt 20 years ago, but they weren't helping me at that point either. VP shunt wasn't an option at that time, but I got one a couple years ago and it seems to work much better.
I would definitely ask for a plan, if they haven't discussed anything with you yet.
Keep us posted!