After how long of being on antibiotics or how many diff ones of failed attempts to treat kidney infection before being admitted in hospital for iv med?

Varies: The primary indications for hospital based treatment would be associated toxicity of condition (dehydration, sepsis) or a bacterial strain resistant to all forms of oral medication.If preliminary sensitivities on the UTI germ show available oral meds and the patient is stable, outpatient treatment is preferred.

Urologist: Urine culture and sensitivity should've been performed before you started any anabiotic's. This helps one know what is the correct antibiotic to kill a given bacterial infection. If you are having fevers and back pain you should have some upper tract imaging such as a ct scan. At this point i would see a urologist.