Not all babies/kids will have a die-off from probiotics, but some will. For those that do experience it, it wouldn’t be unusual to show symptoms of die-off within the first few days of starting the probiotic. This could be increased irritability, crying, worsened sleep, gas, loose stools, etc. It usually only lasts for a couple of days before passing.
It does. She had a bad bout of thrush after we got her home from NICU, where she was given every antibiotic available for pediactrics. She’s been on a variety of meds since so I wouldn’t be surprised if she way of balance. (come to think of it, poor girl really hasn’t been med free from birth)