Austin Mahone -- Hospitalized for Blood Clot

Bad news for singer Austin Mahone -- his rep tells TMZ, Mahone was hospitalized yesterday morning with a 104-degree fever, and he's currently being treated for a blood clot and "extreme inflammation" in his throat.

The rep says 17-year-old Mahone is also being treated for severe dehydration. The rep didn't explain what might have caused the medical emergency.

Mahone posted the above photo to his Instagram yesterday with the cryptic caption, "I've never felt so bad."