Is it possible that a stress fracture not heal?

Yes it is possible: Patients with some stress fractures, such as displaced femoral neck stress fractures and fifth metatarsal base stress fractures, are more likely to have complications such as nonunion. These complications should be monitored closely because surgical intervention may be necessary.

YES: You frequently hear of professional athletes having a stress fracture that does not heal, and they have the best treatment possible! I would order an MRI; if not healing, I would try a bone stimulator. Problems like diabetes and RA, and medications like prednisone, can affect healing. Sincerely, Dr. Latva