Cold twice in a month. Best solution.

Dear sir/mam , I am a active person, since last one I have cold and running nose, initially I started with cetrizine but even after 4-5 days it is not going, now after 4-5 daysy throat also looks congested, I then took Azithromycin 500 for three days but there is no improvement, I am continuously taking hot drinks and gargling twice in a day still condition is not improving last month also I had the same problem but it just lasts for 5-6 days and there after I improved, again it appears after one month , why this is happening again and again. I don't have cough but still when I am forcely coughing I am finding a little bit congestion in throat and chest and mild sputum is coming which is browniss in colour how ever discharge from nose is yello in colour. Kindly tell me the best solution.