It's been 4 months since my spinal tap. terrible head, neck & back aches with shooting pain in my legs. what could this be?

Spinal disease: It sounds like you REALLY need follow up with the neurologist or doc who did the procedure. Have you called the office? It's remotely possible you have a CSF leak after the spinal tap, although most heal on their own after a week of conservative treatment: strict bed rest, avoiding coughing, sneezing, nose blowing, and straining etc. You need a diagnosis to get helped. Hope you will feel better.