Black lab, female, 14 months old
This morning she didn't have any visible swelling on her elbow and when I got back to my house this afternoon, she had this thing:

She's not limping, it's not painful to her when I touch it, there is no visible wound and she seems to be avoiding the wood floors and staying on the carpet. Obviously taking her to the vet is the best option, I'm just trying to get an idea of what I may be looking at.
Appreciate any help!
This morning she didn't have any visible swelling on her elbow and when I got back to my house this afternoon, she had this thing:

She's not limping, it's not painful to her when I touch it, there is no visible wound and she seems to be avoiding the wood floors and staying on the carpet. Obviously taking her to the vet is the best option, I'm just trying to get an idea of what I may be looking at.
Appreciate any help!