It's good that that was dirt and not a sore place forming.
Glad you have a vet that can take a look at her, it does look like Bumblefoot. Hopefully the vet can assess her swollen abdomen while you are there.
Keep us posted.
What does it feel like - fluid filled, hard, soft/squishy?
She may have some fluid in there. Excess fat, tumors, cancer and internal laying can also cause a fullness in the abdomen.
Since she is eating/drinking, laying eggs and is acting normal, I would just keep a close watch on her. Take...