I am assuming the spinal tap you had is a lumbar puncture. Sorry, I don't know how many different types there may be.
eddie, I am so sorry your back hurts. That is rare, but it does happen. Just like the more common headache, a lower back pain as the result of a spinal tap usually lasts from a week up to a year. That is a long spread and a year is a long time to have to tolerate a pain.
This is my understanding but I am not a doctor. The best thing would be to talk with your doctor. At the very least, your doctor will probably be able to give you an effective pain relief treatment.
When inserting the needle they may of hit a nerve. This happens, sometimes. But it will go away use some ice
hey eddie i am daniel. i have had two taps and the shock to the cord and disc is what it really was. i also have had two cordal blocks and those hurt too, time relaxing and perhaps light manipulation on your back can get you into the swing of things it helped me. luck to you............firstname.lastname@example.org