There are ways that bacteria can grow resistant to antibiotics.
1) Be honest about your symptoms with your doctor so that he/she can prescribe you with the right medicine and dosage.
2) Follow doctors orders. Finish your prescription even when you start feeling better. Even though you are starting to feel better, bacteria can still be inside your system and if you don't finish them off, bacteria can develop a way to resist the antibiotic or mutate into a more powerful bacteria (which would require a more powerful medicine).
hope this helped you a bit :)