Pink,
i don't really believe that epidural will cause backache. when i had EJ I took epi, but I never have backache.. then until EV, when I preg with EV, i have some backaches here and there.. then my delivery of EV, I didn't have time to take epi, so NO epi.. BUT I have backache after delivering EV!
So I really don't think epi will cause backache. i think it's the overall pregnancy and how it stresses your body. Even if not pregnant, then it could be the high-heels, the way you walk, the way you sit, bend over the desk etc.. too many factors liao.