Can't find retraction cord

Was doing a D5 on #20 (no adjacent teeth) - Packed two cords as it was going sub gingival. Finished the filling. Took the first retraction cord out but then couldn't find the second cord. Used explorer, periodontal Probe, manual and ultrasonic scaler but nowhere nowhere to be found.

Although it was packed circumferentially but couldn't be found anywhere despite digging on different sides of the tooth. Told the patient that it will be sensitive today and recommended some mouthwash. told her to let us should she experience any swelling or severe pain. Will bring her in couple of weeks.

Any thoughts?