What Causes Pain In The Foot Where Tiny Glasses Went Inside?

Around 7 years ago, I stepped on some glass. It was removed with a tiny incision. Four years ago, I began having extreme pain in the same part of my foot. All XRays, MRI, and sonogram showed nothing but a small amount of fluid in the affected area. I have had shots, wore a crazy boot, taken Lyrica, and a myriad of other medications to no avail. Could this simple step onto a piece of glass cause me this kind of pain? I am at a loss as to what to do.