What English expressions can you use when you feel sick and go to the hospital? How exactly do you describe your symptoms?  

How our bodies feel and behave when we feel uncomfortable?

Let's see some synptoms: 

Vomiting 呕吐

Toothache 牙疼

Sore throat 嗓子疼

Headache 头疼

Fever 发烧

Methods of reservation:

"I would like to make an appointment to see the doctor."

 "I'm not feeling well. Can I see the doctor?"

 "I would like to see Dr Smith."

"I would like a female doctor if possible."

Questions from doctor：

"What's the matter?"

"Can you describe your symptoms?"

"How long have you been feeling this way?"

Answers to the doctor's questions：

"I'm in a lot of pain."

"I've got a headache that won't go away." (to describe a headache)

"I think I'm running a fever." OR "I've got a temperature." (to say that you have a fever)

Descriptions of your feelings：

"I am feeling dizzy."

"I'm feeling nauseous." (to describe the feeling of wanting to vomit)

"I feel pain in my chest."