My Son Is 34 And Has Peripheral Neurpathy After Abusing

My son is 34 and has peripheral neurpathy after abusing nitrous oxide. He had to use a catheter but now he doesn't. He relapsed and used more nitrous oxide. I had him committed as his breathing was difficult.
Now he has foot pain on top of his foot. He thought it was broken but it's not. Dr.'s say maybe gout or a sprang. He's overweight but never diagnosed with diabetes. I read on this website that it could be toxins and a B12 defiency. What's your opinion?