I think I have damaged my sciatic nerve, I don't know how but I have random tingling and numbness in my feet, legs, arms and hands. Why could this be?

See your doctor. The sciatic nerve is actually a bundle of nerves that starts in the low back and supplies the lower extremities only. Numbness and tingling of both feet, arms, and hands is not consistent with a sciatic condition. See your family doctor or internist to find the cause of your symptoms.
See below. Damage to your sciatic nerve would not dause arm or hand problems.