Hi Paul, welcome to the group! I'm afraid not many doctors anywhere have much information on IIH. It's a rare disease that isn't a threat to life, so very little research has been done. That's why these forums are so important. I know we have other parents as members, so hopefully you'll find some support and guidance.
I'm so sorry to hear your daughter didn't get any relief from the spinal tap. I hope the medication will help keep pressure down, so she can find some comfort once she recovers from the procedure. It sounds like they've done the typical testing and medication is actually the best case scenario, if it works. There are procedures and implants that can help, but hopefully she can manage her symptoms with medications.
Please look through the site and let us know if you have any questions.