MY GRANDSON IS 11 YO AND IS HAVING EPISODES WHERE

MY GRANDSON IS 11 YO AND IS HAVING EPISODES WHERE HE GETS VERY WEAK AND PALE. LAST NIGHT HE ALSO HAD AN EPISODE OF N&V. HE HAS SEEN CARDIOLOGIST AND WORE A MONITOR FOR 2 WKS AND THEY DID NOT FIND ANYTHING. I AM WONDERING IF IT COULD BE HYPOGLYCEMIC EPISODES. HE HAD EATEN ABOUT 1.5 HRS PRIOR TO EPISODE LAST NIGHT AND HIS BLOOD SUGAR WAS 97. WHAT DO YOU THINK?