What Causes Swollen Lips With Rash On It In A Child?

HI MY SON HAS EXTREMELY RED LIPS, IT LOOKS LIKE HE HAS LIPSTICK ON. HE IS 10 YRS OLD. TWO WEEKS AGO I BROUGHT HIM TO THE DR. CAUSE HE HAD A FEVER AND THEY DIAGNOSED HIM WITH STREP THROAT AND WAS PUT ON ANTIBIOTICS. ABOUT A WEEK AGO HE HAD AN EPISODE WHERE HIS LIPS SWOLLED THREE TIMES THERE SIZE AND HE ENDED UP WITH A RASH. I BROUGHT HIM BACK TO THE DR S FOR THAT ALSO AND THEY SAID IT WAS VIRAL. I M WORRIED NOW, COULD THIS BE SOMETHING OTHER?