Could be from a bruise she got while playing, or a sting she got some time during the day. When Cole and Ember were puppies growing up together, we had lots of mysterious lumps. My best advice is not to play with it or check it frequently. hazel has been known to irritate lumps even more because she can't resist checking them...and the extra irritation tends to make them bigger
"We are--each of us--dying; it's how we live in the meantime that makes the difference."
"It's not what you gather, but what you scatter that tells what kind of life you have lived!"
"Be kinder than necessary, for everyone you meet is fighting some kind of battle."