Are you tapering off the benzo it can take a long time.Is your doc doing this with you or on your own?
The ashton manual has great information on how to taper benzos.

I am very sorry that you have been so ill. Yes double up on fluids as we don't want you to get dehydrated. But I think you knows this ,can you drink gatoraid clear no artificial colors. but will give you some other nutrients, I think electrolytes.
again I am so sorry your ill.Thanks for checking in. Anxiety is probably rebound for discontinuous the benzo.