Feeling shaky whenever I do physical activity?
I'm a skateboarder and not only that, but I'm addicted almost to doing things outside. I've noticed in about maybe the past two months whenever I do something outside, even for like 3 minutes I start to feel like I'm going to faint and all shaky. I eat pretty much as much as I can, so I don't think that would do it (Just had 2 cans of Spaghetti O's and a McDonald's quarter pounder meal, then I skated for a bit and started to feel faint.) What could make me feel this way?(Yes, I know that sentence sounds like a song...) Thanks!
Well I'm pretty much underweight (80 pounds at age 13, lol)