Hi, I have an Indian Runner duck that has been limping and has what looks like a bubble on one of her toes. It has grown bigger in the last week. Originally it just looked like a small scab. That whole toe seems to be a little swollen. Picture attached. Any thoughts on what it might be and how to cure it? If you can see in the picture it is her left-most toe on her right foot and it is that bubble just before the claw. Thank you for any help!