You need to consult a Neurosurgeon and he will tell you whether you need opinion from vascular surgeon or physician

It can be due to neurological reasons..due to ageing lower spinal bones will go for damage and lead to nerve compression in the back leads to pain whereever the nerve goes.. It needs neurological examination and may require imaging if necessary.. Swelling of the leg usually not related to neurological reasons..so consult a neurosurgeon and follow his advice...