"Just turning around" as in making a U-ie?

I don't know the specs on your new bike vs. the old one, but it sounds like it's probably lighter and has a shorter wheelbase, and if so, it may take a bit more attention to keep it balanced.

Also, were you looking behind you where you wanted to end up, or at the ground? It's really important to look THROUGH your turns, look where you want to go, for a lot of reasons. Glance at the ground to make sure there's nothing you don't want to run over, then look up. Looking too hard at the ground is a pretty good way to wind up on it.

Hope you feel better soon. Pain is exhausting even when your injuries are minor, so get plenty of rest.

PS - good thing you DIDN'T put your arm out. That's how people break their collarbones.