Postpartum tingling

6 months ago I gave birth to my 4th child by c-section under epidural. The anesthetist told me he had to keep upping my dose because my CNS 'was not normal'. Since 10 days postpartum I have been having tingling in my arms and legs, on and off, sometime one leg, sometimes both, sometimes arms. There has never been any numbness or weakness. I have had bloodwork and MRI that came back clear. The symptoms themselves are not that bad, but the concern over what is causing it is. Any suggestions?