The Commission or any member thereof may, upon the application of either party or upon its own motion, appoint a disinterested and duly qualified physician or surgeon to make any necessary medical examination and to testify in respect thereto; however, the provisions of this section shall not apply to determination of whether an employee died of pneumoconiosis or any chronic occupational lung disease, which shall be governed by the provisions of § 65.2-513 and the regulations promulgated thereunder. Such physician or surgeon shall be allowed travelling expenses and a reasonable fee to be fixed by the Commission. The fees and expenses of such physician or surgeon shall be paid by the Commonwealth.