I feel very bad.
我感覺不太舒服。
Shall I call a doctor for you?
要我幫您叫醫生嗎?
I'm sorry to hear that you are not feeling well. What's the problem?
聽說您不舒服,我很難過,您哪里不舒服?
Have you had any fever or any other symptom such as a sore throat or a cough?
您有發燒或其他如嗓子痛、咳嗽之類的癥狀嗎?