I asked him. He couldn't recall the exact figure. But he told me the last time he had it measured was about 2 months' ago, and it was normal according to the doctor. But you're right that he gets pretty apprehensive when in a crowded, especially a new environment very foreign to him.
Medicated oil is the temporary cure (Chow Kow). The real cure is you must bring him to a real good KTV.