has this happened to anyone else's little one?

EVERY time DD walks lately, she falls forward. And I don't mean a stumble - I mean a full on face plant. Several times she has landed flat and had marks on her chin and forehead from the impact. Of course she cries... and cries... and cries. It has gotten to the point where last night she actually reverted to crawling. I've checked her pants and they're not too long. The shoes are the right size and ones she has worn plenty of times before. It's really affecting my happy little girl and I'm at a bit of a loss... so if it has happened or you know why it might be happening, please reply!

MG