TingWai,
Forget to answer you la.
I asked a Medical Doctor, not the oncology/ENT doctor, he said may be you are sensitive to some food, don't worry, he said you should pay more attention to what you have eaten, and don't eat the things for a week to see whether the condition is being better or not. If yes, don't eat the things, and if not, he also suggested you to take sample to check.