Recently, I saw a patient with numbness in the lower limb that presented similarly to sciatica. After doing a neural length test this was ruled out. However, palpating the piriformis muscle caused pain and reproduction of his symptoms. Piriformis causes symptoms exactly that of sciatica eg: numbness in the foot. By using trigger point release over the piriformis muscle, the patient's symptoms dissipated. So maybe palpate this muscle checking for tightness or pain and go from there.

Best of luck