I'm sorry they've left you completely in the dark..no wonder your frustrated and scared! They use LP to measure pressure, but people w/ IIH usually find some temporary relief once CSF is drained off. It is only temporary, so you could just be experiencing the high pressure headaches again..if they feel exactly the same. Linda's right, a low pressure headache can happen after a spinal tap if fluid continues to leak, so they do a blood patch to seal the leak. If you do get relief when laying down, then it's probably a leak. Your doctor may have ordered the blood patch based solely on your symptoms because it's a typical procedure, but someone should evaluate you prior to the procedure. I assume the person doing the blood patch will do it, but I would definitely ask questions before you let them poke you.
In the meantime, try drinking caffeinated beverages, cold packs for swelling, and lay down as much as possible..the flatter the better! Your high pressure headache can get worse if you push through pain, but low pressure headaches will also get worse because you leak more when upright. Sometimes, they suggest laying flat as many as 7 to 10 days, so try not to worry.
It sounds like you've been on Toprimax for awhile, but if it's new it can also make headaches worse. Unfortunately, everyone responds differently to meds so it's all trial and error. You might try keeping a symptom log..there are examples in the Useful Guides and Print Outs section.
I hope you find some relief soon..hang in there!!!
[You must be registered and logged in to see this image.]Julie