Please explain if it is possible to obtain phrenic nerve damage from whiplash?

While it is not. Likely, the possibility is there. Did you have nerve damage to any other structures. The roots of the phrenic nerve are in the cervical region (neck) and the body of the nerves run along the front of your cervical vertebrae, so trauma could, theoretically injure the phrenic, although it is not a common injury, especially in isolation.