I really need some info on what may be a suitable alternative or a regime to administer it but much more slowly.
No you don't. You need to trust your daughter's doctors to find a suitable alternative. There are many different antibiotics that might be suitable for such an infection and she is unlikely to react badly to more than a few different types. If one doesn't work or disagrees with her, then you simply move on to the next.
Your job is not to be her doctor: it's to be her Dad.