What does the other side look like. When they're overweight, they sometimes pooch out right there above the leg, but it's both sides. If only one side, it may be an abscess. The shell looks a little red right at that spot - or that may be just the photo.
I know my smallest red foot pooches out due to being a bit overweight possibly but to me that looks different like red & may e painful? Does it feel like a nodule? Because if its just extra skin it's pretty soft. I hope your red foot is ok? Is your red foot acting normal? Walking ok?
Have you taken your finger and gently pushed the leg and skin aside a bit and then run your finger along the inside of the shell to make sure that there is not a sharp spot?
In case that she have something in there and I take it out, what I can put in there to heal that area? Like a triple antibiotics or something like that!!
You can offer a long warm water soak and then apply a touch of antibiotic ointment (but I would try first just clean warm water soaks and see if that will allow some relief, no need to expose to antibiotics if not necessary---you want them to be most effective if ever needed so not overuse)....if there is something in there/stuck to the tort then the long warm water soaks may help....
Last night did a check up on the area and the bump was reduce to half the size of the one on the photo and is more like her skin color not the white skin.