After reading a paper the vet gave me after my pups had shots it list a couple of things to watch for....such as hives, swollen face, itching, lethargic or being restless, difficulty breathing and so on...I don't think you have anything to worry about though since you have not mentioned anything like that happening other than the biting of the feet. My Leila always bites on her back feet....she is allergic to grass.
As for her poop being darker...that could be caused from the antibiotics she is taking. You should contact your vet and ask let them know if she is still having the same symptoms.
__________________  Leila  Champion Mila |