My 4 year old female Rottie/Shep mix went to the vet last week because she seemed unusually tired, sometimes a little stiff when getting up from a lying down position, and just sort of off her usual game. Those symptoms persisted for a little over a week before I took her to the vet. Well, the vet gave her a clean bill of health and said that he wished all of his patients were as healthy as Maxie. The day after her vet visit Maxie was back to herself - good energy and healthy look in her eyes, but now I noticed a lump on her upper lip. It's sort of white and reddish and it's just on the rim where it overlaps her lower lip and today it seems bigger than yesterday. Any idea if this lump could be the result of a virus that her body kicked last week and now it's coming out in a visible virus on her lip? Since we just went to the vet 6 days ago, I'm wondering how long I should wait before taking her back. Is it ok to keep an eye on it at home for a few more days?