OMG. Wow, that is really weird. So there's nothing stuck in her paw? Maybe try taking her for shorter walks after she heals? I'm thinking either something got stuck in her paw or she sprained or pulled something.
My prayers are with ya'll - please keep us updated!
edited to add:
as for her weight, she does look to be a bit on the smaller scale of the EB range. If she's already 45 pounds at 1 year, she still has some growing to do. My girl is about the same size as yours, my girl is 5 years old and weighs 48 lbs. Our vet has told us she needs to lose a few pounds, too. I don't think she looks fat, but if she's only 1 year old and weighing in at 45 lbs, and she's still gonna grow, they yes, maybe she could stand to loose few.
Hope this helps?