Sarah, this may not be related to your case at all, but I had a sudden recurrence of pain a few weeks ago after a very successful double fusion at L4-S1. I had fallen over my dog while going upstairs at night when the light went out. I had also recently started doing my artwork again, which involved leaning slightly over a drafting table.
I went to my chiropractor, as my surgery was done out of country, and with just a tiny bit of work with an activator tool and pressure points, he relieved what seemed to be pain in the exact area of my fusion. It turned out to be SI ligaments, and I need regular treatments to keep the pain down. But it is definitely not related to the original surgery. The relief made me cry in his office.
I jumped to the worst scenario, because the stakes were so high. I hope that this proves to be something similar for you. Perhaps a good osteopath/massage therapist may help?
PS: My chiropractor does not and has never done the 'bone cracking' that so many spine patients fear. I'm amazed at how little he does fixes a big problem.