Multiple Lung Spots

bkgrnd:  5 years ago when diagnosed with breast cancer I had a CT scan that showed a "misty" spot on my left lung.  All the docs said it was probably nothing and ignored it.  Last year I went to the emergency with chest pains.  They performed another CT scan and notified my PCP of the results which showed a solid mass on my left lung and a "misty" spot on my right.  A thorasic surgeon did a bronchialoscopy.  The results showed some inflamation (inflammation), but no cancer.  A follow up CT (two weeks later) showed several spots of various sizes in both lungs.  The doc didn't want to do any further biopsy, not knowing which spot to biopsy, and said there were not any real changes.  (I had never been told before that there were several spots in my lungs, only the one in my left and the one in my right.  I am scheduled for another follow up CT in June and then again in September.  What are the other possibilities besides cancer, that cause these spots?