Why do I feel so shaky and weak sometimes?

I was playing video games laying in bed and all of a sudden i got really Tired/faint feeling and i felt all shaky inside. I got up for a minute to use the bathroom and when i came back to my room and sat down i was shaking so much. I made a pbj bagel and was struggling to hold the spoon cause i was shaking and felt weak.

Then i checked my blood sugar before i ate the bagel and it was 81 which is apparently normal. I ate cereal a couple hours ago so i didn't think it should be low anyways.

Currently eating the bagel and very very slowly starting to feel a tiny bit less shaky and weak.

This has happened to me before a few times, but i wasn't able to check my blood sugar when it happened until this time.

I just don't know why i feel like this sometimes, and Google keeps telling me it's hypoglycemia but apparently it's not