Here's the article and link from an article on Livestrong about black seed treating diabetic neuropathy. You mentioned that you were pre diabetic, so the high blood Sugar may be what's causing the pain.
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Diabetic Neuropathy
Diabetic neuropathy is a condition that causes pain in the extremities, especially the toes and feet. The pain is associated with elevated blood sugars over time. Eventually, the nerves are damaged and the nerve tissues become inflamed. Acute pain or chronic pain may result. Not all diabetics develop this condition if Sugar levels are well controlled according to the National Institutes of Health. Black seed oil contains a component called gamma linolenic acid, GLA, which has been shown to reduce pain associated with diabetic neuropathy. These results were apparent after a six month study as reported by the University of Maryland Medical Center. GLA has anti-inflammatory qualities."