In My Check Up I Was Found To Have A

In my check up i was found to have a suspicious opacities in my left lung. No coughing, but i observed that i had phlegm at times . but previous to this when i had my xray last October only, it was found in my right lung a slight hazy portion. From there, i was given an antibiotic for a week ..now as i am having an annual physical exam, i was diagnosed to have suspicious opacities and to undergo apilordophic xray...was this a serious thing?