7 year old pooping in pants

Instead of disciplining, I would wait it out and just support her. If you've ruled out a medical reason or a deliberate action on her part causing this issue, then it's likely stress or anxiety. When it happens, I would have her clean herself up, and not make a big deal out of it. If it's related to stress or anxiety, then giving her a consequence or making a big deal of it will not help matters at all. Just a "Oh, I'm sorry you had an accident honey, why don't you go get cleaned up and get a new pair of panties and pants?" If it is stress and anxiety, then address that aspect of it so that she can express her feelings verbally. Either by discussing whatever is causing the stress, remove the stress, or even counselling if you feel she needs that.