Here is how Taking care of Yuna goes in A Sick Day for Yuna.
Princess Luna: How is she, Dr. Horse?
Dr. Horse: (looking at Yuna's temperature) It seems to me that Yuna's catching Pneumonia.
Princess Yuna: Pneumonia? (coughs) How long do I have until I'm better?
Dr. Horse: I can't say for sure, Princess Yuna, But I did invite someone who can.
Princess Yuna: Who?
Baymax: Hello, Princess Yuna.
Princess Yuna: Baymax, (coughs) What're you doing here?
Baymax: Your Aunt Celestia invited me to help Dr. Horse with the young foals just for today.
Princess Yuna: So, (coughs) How many days or weeks until my Pneumonia gets better?
Baymax: I will scan you now and find out. (scanning Yuna) Scan complete.
Princess Yuna: Well?
Baymax: You have only three weeks until your Pneumonia will be cured.
Princess Celestia: I'll have to get help, I'll be back soon.
Duck: Thanks for your help, Baymax, You've done your part for Yuna, You may continue what you're doing at the hospital.
Baymax: As you wish, Duck.
Duck: I'm sure you'll get better in no time, Yuna.
Princess Yuna: Thank you, Duck. (coughs)
Meanwhile, Celestia spoke to Discord and Catrina.
Princess Celestia: Discord! Catrina!
Discord: Oh, Celestia, What a pleasant surprise.
Princess Celestia: I need some help from the two of you, Yuna is terribly sick with Pneumonia.
Catrina: How awful, That poor poor filly.
Discord: Almost as awful as the time I got sick after I faked my Blue Flu to get Twilight and Cadance's attention.
Princess Celestia: Will you two help me take care her until she gets better?
Catrina: Of course, Princess Celestia, It will be our pleasure.
Discord: (dressed as a doctor) Anything to help a good friend in need.