Is it bruises? Did she bump or slam hard on something?
Take her to the vet because self-diagnosis on dogs is always very difficult.
Experienced vets should know which breeds are genetically prone to which disorders. And for some reason alot of dog disorders are lumps.
Get it to the vet asap.
Hope things turn out fine over at your end.
My little one had a tumor removed from the tip of his left ear. When the doctor told me and my dar about it, my vision blurred for awhile, a slight headiness set in, and I couldn't concentrate on what the doctor was saying after that. This was the first time owning an adult pet dog and this happened during 'my watch' (under my care) so I was naturally upset with myself for failing to raise the red flag earlier. He was so chirpy and healthy and I didn't notice a thing missing.
After this episode, I realized he means the world to me and my dar. And it's only recently, we are planning to get a Holland Lop to provide companionship to him because we are both working, and he looks like he could use some company. But as to "how to break it up to him", well, we are working on that.
Go to a nearby vet quick quick!