Is it possible for an epidural cause chronic back pain?

Epidural: If the epidural was done correctly and by a md properly trained - then no you should not have back pain.

Highly unlikely: It would have to be a significant complication like an injection into the thecal sac rather than the epidural region or cause a blood clot (hematoma) or a allergic reaction causing a local response to the neural tissues. These are very rare issues. More likely the reasons sought for the injection cause the ongoing pain. If given for delivery even less likely for chronic back pain to develop.