Regular Cold and cough type allergy.

Hello Doctors, My father is 54 years old. He has diabetes and BP.. On an average his BP is around 132/85 and Sugar level is around 250.. He has a problem of running nose and sneezing and slight cough on a regular basis. He calls it allergy and and even take mild cold medicine presicribed by doctors here but since we live in very small town I am not sure how reliable this can be. I request you to please advice whether it's a allergy or not and how it can be treated.. he starts to sneeze with slight change in temp.. it can be early morning or afternoon when it's sunny and even with strong perfume. Please let me know what should we do and what type of medication should he take as he is diabetic regular medicines can be problematic.we got his chest X-ray(attached). Kindly advise!