Go back to the vet and ask to get a culture done.
Oral antibiotics does nothing for reptiles because their metabolism is so slow. Ask to get injectable antibiotics. And by getting a culture done, you can choose an antibiotic that will target the specific type of RI. There are different types of RI and many types of bacterial RI, which is the most common form. Some antibiotics are not effective towards certain types of RI. Many default antibiotics like Baytril, for example, are ineffective because most bacterial strains are resistant to it. So that's why it is important to find out the exact type of infection so you can choose an affective antibiotic accordingly.
Bump up the hot spot to 95.
My vet tells me not to have any humidity because moisture + heat = breeding grounds for bacteria. However, I have heard some vets suggest high humidity for RI. If you choose to go humid, make sure your air circulation is good. Stagnant air is more likely to harm your snake than good air flow.