The other morning in the very cold snow, winnie let out a yelp and picked up her right hind leg. we checked it out, nothing seemed wrong, and she could run and play almost immediately afterwards. In the last two days this yelp hop and then fine thing has happened a few times while playing (mostly outside) but because the outside has been so cold we figure that was what it was. Then tonight, again in the snow, she let out an incredibly intense and sustained yelp/whine and picked up her right hind leg again. this time she cried for almost 30 seconds to a minute and her walk did not return to normal as quickly this time. Has anybody had this issue or does anyone have any suggestions? she's only 15 weeks old and we're thinking an expensive vet visit is in order.