Winnie Worries

The pups are now three weeks old. Growing, playing and eating. As most thrive we become more concerned about Winnie. The smallest puppy, she was also hard to revive at birth. She is gaining weight but it quite a bit behind the front runners, mind you so is Beth, but I have no concerns for Beth. Winnie seems to have suffered from colic on and off since Monday. Following a telephone consultation with the vet we put her back just on her mothers milk, she feeds well and though small doesn't get pushed out.
Our main concern is that we have both observed that she is different, she lacks something, a spark a playfulness that all the others seem to have. She interacts less and sleeps more. Maybe she is just behind, but I can't help but worry about her. There is no doubt that if she doesn't catch up then we will have to take her to be checked out. When is the right time to do that? Well I don't know, but we'll see how this long weekend goes and reassess how she goes with feeding and her demeanor daily. I'm worried, as is my nature! Come on Winnie, this world can only be a better place with you in it, yeah, the world really needs a Winnie!