Have you seen a surgeon about your options? It seems to me that a skilled Nissen surgeon will know the best path to take. Who did the testing? Joy has a point, but it's definitely time to get a medical opinion on your path forward.
I don't know where your Nissen was done and by whom, but now that you're having a complication, if you can get to a large center where surgeons have more experience with problems, it could be to your benefit.
Very best of luck!
Words of wisdom by Eckhart Tolle:
"Whatever you fight, you strengthen, and what you resist, persists.”
“Worry pretends to be necessary but serves no useful purpose”
“Accept - then act. Whatever the present moment contains, accept it as if you had chosen it. Always work with it, not against it.”