Hi Adam - I've had that reaction a couple of times too, it comes when I've been working out hard and haven't eaten much, so I'm assuming it goes with very low blood sugar. I avoid it now by having some extra carbs before a big workout. It seems to allow me to work out harder and doesn't slow down my weight loss - if anything, the better workouts speed it up.
It wouldn't hurt to get yourself checked out (though I never have) but I don't think its too serious.
Good luck in your journey. I was quite shocked by my bf at the start, cos I didn't consider myself very overweight! Still, its come down nicely, as yours will do too.
Take care, Jay