your symptoms do sound like cough headache- this can be due to primary cough headache, or seconday causes, which have been ruled out by CT and MRI. Primary cough headache can last up to 2 years, so this is still the likely diagnosis.
The slight increase in your CSF protein may have been due to a traumatic tap (blood got into the tube).
I would have your creatinine followed up on to make sure it hasn't risen- creatinine and GFR are indicators of your kidney function.
I would either follow up with the same neurologist, or another one if you prefer another opinion, because there are other treatment options, and you shouldn't suffer unnecessarily.
Hope you are feeling better.