Hi! Just offering support for your fast! You CAN DO IT. Keep going.
I say this because it sounds like you really want the fast and believe in it for yourself and feel healthy with it.
In my humble opinion the fast itself will help the infection but it is so hard to know what to do!! If i were in your position I would take the Antibiotics given by the doctor and also continue the fast. I would ask the doctor what the consequences would be if I DID NOT take the Antibiotics for a few days, and fasted. Ideally this would be a doctor who would be receptive to fasting and who would know what to do. And you could tell the doctor the full situation (just that you are fasting) and not be afraid to tell him the full situation. But if not, maybe there is a doctor at TrueNorthHealth, a fasting clinic I have looked up in the past, who could answer your question or refer you to a professional who could.
It seems like you are in a genuine conflict about fasting, needing to fast but being unable to put aside certain concerns. I don't want to stir up trouble by saying something like, "Oh, just fast and everything will get all better, forget the Antibiotics ." Because who knows what could happen. I know it is hard to find an MD receptive to fasting. Well,... I know of one Joel Fuhrman MD (you can google all these people/places; they are very web-available) who runs a practice who could address your questions... I wish it were not so hard to get answers!!! i got in touch once with one "DR. Bernarr" on the web. i think he is in Santa monica, California. He seems kind of available and might be able to advise or refer. Just know that my heart and sympathy are with you and I support you. I know you will succeed in your fasting goals and I know you will get better.