You are right about the "survival of the fittest" concept applied to the bacteria when a specific antibiotics is applied Its all about that particular antiobiotic resistant gene within the bacterial cells (which can be transferred from one to another iinm).
It is because of this that many researches are being conducted in search for other types of antibiotics from many different sources, particularly from fungi etc.

As for those "other medicine" use to treat bacterial infections? Are there any? Aren't all of them antibiotics?

iinm - If I'm not mistaken

I am also a noob in this since I'm not even studying medical stuffs
I've just Googled up Clarinase, and subsequently Pseudoephedrine and Loratadine... these medicines are prescribed for those with flu (you are right about that one), but they function as stimulants for dis-congestion only it seems, doesn't relate to killing the bacteria at all

Antibiotics are powerful medicines, which is why Doctors (both knowledgeable and non-knowledgeable) often prescribe them to kill off everything (including good bacteria in your system)