Welcome to Just Answer and thanks for your question. This is an interesting situation. You see, if it hurts to pee in the toilet, it would also hurt to pee in the diaper. It is the urine going through an irritated urethra that hurts. If she is experiencing no pain going in the pull-up, then she probably isn't in any pain any more regardless of where she urinates. That doesn't mean she didn't have a minor infection at one time that was cleared by the antibiotic. At this point it may be more anxiety than anything else. It's hard to say what is going on with a child this age. It could be a bit of recidivism to pull-ups because she is unsure of herself as she goes through development milestones. The pull-ups may be a security blanket for some toddler angst. I'd give it a week and start the training process over again.