I have a headache.
I have an earache.
I have a toothache.
I have a stomachache.
I have a backache.
I have a sore throat.
I have a fever/temperature.
I have a cold.
I have a cough.
I have an infection.
I have a rash.
I have an insect bite.
I have a sunburn.
I have a stiff neck.
I have a runny nose.
I have a bloody nose.
I have a cavity.
I have the hiccups.
I have diarrhea.
I have a chest pain.
I have shortness of breath.
A pandemic breaks out/spreads.
I caught the flu/got infected from him.
You should rest in bed.
You should take a pill/some medicine.
You should go on a diet.
You should exercise.
You should get acupuncture.
You should use a walking cane.
You should use a wheelchair to move around.
You should get a blood test.
You should have a physical therapy.
You should have a surgery.
You should see a doctor.
You should see a dentist.
You should wear an antibacteria mask.
You should be kept in quarantine.
You should keep a distance from others.