I am on antibiotics again but saw a less experienced doctor who didn't really think a sputum sample was necessary. I have had a hacking cough for a week and a lot of lung pain but the sputum sample from last week was inconclusive. I am wondering if I have a chest infection but started them as am in pain. Unfortunately, I wasn't thinking and started taking the antibiotics without doing the sample. If I give a new sample tomorrow having taken one antibiotic will it affect the sample?