Hi Kerri...I know Chiari symptoms can cycle...come and go....and surgery does not get rid of symptoms, it is meant to restore CSF flow and slow progression.
It is possible you have scar tissue or something causing another CSF flow.
I don't recall the aspects of your surgery or related conditions....but it could be that too.....
Chiari does not go away, surgery doesn't fix it....and sadly it didn't help you as much as you would have wanted....not everyone is.....and I am not sure of anyone that is completely symptom free post op or years later....for me, I am better then I was before surgery and now better then a few years post op...BUT I still have symptoms and issues....I never got behind a wheel of a car again....I just can't.
I am so sorry you are doing so poorly and I hope you get answers with the MRI.....remember to get copies of it and the report.....and keep us posted here.
Prayers sent out to you for answers and relief.