Hilar Adenopathy

I'm 29 years old male. Last two month, I've got a cough for 4-5 days, and fever 2days. I saw a doctor and she let me do the chest X-ray. The result was "hilar adenopathy on the left, and a right lower lobe infiltrate". The doctor told me that I've got pneumonia, then she write the precription for the antibiotic. After taking antibiotic (Z-pack)for 5 days. My fever was gone but still cough. She give me another antibiotic (Levaquin) for 5 days. As a result, the pneumonia was gone, and cough was fade away in about a week.  I have no other symptom. My question is that what kind of disease could be from the hilar adenopathy that see in X-ray?  Can I just follow up the hilar adenopathy by doing x-rays every 2-3 months and see if it's enlarge or not?   (Actually, I have waited for 2 monthsand just did another X-ray. The result still found the same..but the node is not enlarge).... Can I still just follow up as I did?  Thank you very much for your kindness.