First of all, keep in mind that I am unable to diagnose you because I am unable to examine you, this forum is for educational purposes.
The symptoms and story you describe is complex and there is a lot of data that I do not have. That being said, I would be concerned about the following, refractory hydrocephalus, sinus venous thrombosis, spinal cord ischemia and/or progressive neuropathy (unrelated to your pseudotumor and shunt). Hydrocephalus generally causes a triad of symptoms: gait abnormalities (feet stick to the floor like magnets), dementia (memory/cognitive problems), and urinary incontinence. Refractory hydrocephalus occurs rarely, but is most often due to shunt infection and/or malfunction (I think this is less likely, given the symptoms you describe). To test for this a lumbar puncture can be preformed and an opening pressure obtained. If high, then 30 cc (high volume) of CSF can be removed to see if this impacts your walking.
Many patients with pseudotumor cerebri (also known as benign intracranial hypertension-BIH) have obstruction of CSF resorption back into the venous sinuses. Sometimes this is due to blood clots in the venous sinuses that can then increase in size and cause venous infarcts (strokes, often with a hemmorrhagic component). In your case, I would be concerned about a stroke in the anterior cerebral artery territory given your leg dysfunction. To test for this I would suggest an MRI of the brain with an MRV (magnetic resonance venogram). If clot is seen in your venous sinuses, then anticoagulation with coumadin would be indicated.
The classic "I woke up from surgery and now my legs won't work" senario is caused by low blood pressure during surgery that interupts blood supply to the anterior spinal cord (most often from the artery of adamkowitz). This may be hard to identify on MRI, depending on when the MRI was done in relation to the injury. This would cause a weakness, without sensory problems, and can be diagnosed by EMG. A SSEP (somatosensory evoked potential may also be helpful to evaluate the sensory fibers.
A progressive neuropathy/myopathy is also possible, but would be unlikely to be related to your pseudotumor cerebri/shunt revision. For this I would recommend a second opinion EMG at a major academic center and blood work to screen for serum/urine monoclonal proteins, ANA, B12, ESR, CRP, copper, vitamin E, and paraneoplastic panel.
I would also like to encourage you to stay in physical therapy, because regardless of the cause of your leg weakness, it will only get worse (contractures, etc) if you do not keep them mobile.
I hope this has been helpful.
I'll have to ask her about the cidp if I see her again.