The "Writing's On The Wall" singer has been struck down with the illness and has been left in agony with his swollen glands, reported Femalefirst.
In an Instagram post, he revealed: "Feeling very sorry for myself. Throat Glands are so big. Feel like I have a tennis ball down my throat (sic)."
Despite his illness, Smith was able to unveil a cover of Amy Winehouse's "Love Is A Losing Game" taken from "In The Lonely Hour: The Drowning Shadows Edition" - the new special edition of his debut album.
