I have an Olde English Bulldogge who was also the runt of the litter. She has had the same problems since we got her at 7 weeks old from the breeder. She has eaten the same food since birth (the very high end organic kind). We have taken her for blood tests which have come back negative, had her on anti-biotics as well. Nothing has changed.
Did you ever get a response from this? If so, let me know!