I have no medical training or background but I think finding a specific cause can be difficult for most people. There are a couple of sites I really like for learning more about neuropathy that you might find helpful.
-- Neuropathy Commons: https://neuropathycommons.org/
-- Foundation for Peripheral Neuropathy: https://www.foundationforpn.org/

I shared my neuropathy journey in another discussion here - https://connect.mayoclinic.org/comment/310341/. A few years ago I made some lifestyle changes to see if I could help reduce the numbness I have in my feet. Since I've been in the pre-diabetic category most of my life and it runs in my family, I've always been worried about getting diabetes but it's never progressed that far. I recently learned about the Metabolic Syndrome and most doctors don't mention it but I fit that category as do most people that are pre-diabetic. So, I started a low carb healthy fats and intermittent fasting diet. It has helped me lose a lot of weight and feel better but the jury is still out to see if it will help my neuropathy. Here's more information on the Metabolic Syndrome if you are interested:
-- The Metabolic Syndrome and Neuropathy: Therapeutic Challenges and Opportunities: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3881591/
-- Metabolic syndrome as a risk factor for neurological disorders
https://pubmed.ncbi.nlm.nih.gov/21997383/