Green bubble

Cam

So last night I was playing with my 12 week old puppy and noticed she has a greenish pus filled blister on her belly. I was thinking it looked like an infection. She stepped in an ant mound a couple days ago. Maybe an ant bite got infected or something? Has anyone else seen something like this? I’m calling her vet today, I just wanted to see if anyone has seen anything like this. Stuff like this always makes me freak out and worry.