CMD means corticomedullary differentiation.
Loss of CMD is one of the sonological characteristic seen in a neck ultrasonography it can be seen in various conditions including infections like tuberculosis as well as certain benign and malignant tumors. This single characteristic cannot lead to a proper diagnosis. A tender mobile lymph node of short duration is mostly acute cervical lymphadenitis. A proper history would help in ascertaining whether one is dealing with acute or chronic cervical lymphadenitis.
Next Steps
If the duration is short... Patient can try a course of antibiotic and analgesic and anti edema agents.
Source of infection should be checked and dealt accordingly.
Health Tips
Consult an ENT doctor at the earliest.