It's totally normal for a pre-existing, long-standing problem that was caused by either GERD/acid, or your hernia, to take time to heal. It didn't take 6 months for your lungs to get to that point, and it will take longer than 6 months for them to recovery.
That's why around here we're always reminding each other that it takes a full year for all the healing to occur. I even found improvements into the second year.
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.”