A frog in someone's throat

Meaning:

If you have a frog in your throat, you have a sore throat, or your throat is dry, and have difficulty speaking
because you want to cough.

Example:

In a speech contest last year, she suddenly got a frog in her throat and had a hard time speaking.

A: Why don't you sing with us in our next concert this Friday?
B: I wish I could, but I caught a cold and have a frog in the throat.