[cypher]

It's impossible to say what it might be from photos, from the position it could even be a pouch problem.
Get her a vet appointment as soon as you possibly can, once you have a diagnosis then you know what the options are & how best to care for her.

ETA I just wanted to add a bit more in case you're totally unsure what to expect at the vet, it does depend on what they find but if it is an infection then she will need antibiotics which should clear it up for her, she may need metacam for pain relief too, even if she doesn't appear to be in pain they are very good at hiding it. If it turns out to be a growth of some sort then surgery is a possibility, it is a big risk for small hams but they can & do come through surgery ok so don't rule it out until you've discussed things with your vet.

Good luck with her, let us know how it goes.