If my blood sugar is low how long would it last? mines been three days of shaking very bad which i do when i'm in pain, or could it be neuropathy

How low is low?: Hypoglycemia (low sugar) can result in shakiness. However, having low blood sugar in a non-diabetic is generally due to lack of eating adequately. I notice you didn't put down diabetes as a condition. Are you not eating properly? I doubt your shakiness is due to any neuropathy. You asked the other day about telling between shaking from muscle weakness in the legs vs. neuropathy as well.

Low blood sugar: Of course, pain can cause a person to shake or shiver too. Normally low blood sugar lasts only a short while. It stops within seconds when juice is consumed. It tends to occur in people with diabetes, not so much in people without diabetes. Combined with your other questions, your pain level and neuropathy are probably causing this symptom.