Cough and cold problem. I clear this?

For the past 21 days iam having cough there is no fever and body pains but little bit itchy feeling in throat.I have consulted a physician in a charitable hospital and he prescribed x ray and tb medical tests.The reports are normal and he prescribed me one antibiotic tablet and gocof syrup, but still the cough is not cured.Again he prescribed me pulmonary function test.What's this problem and how can I clear this?Iam a teacher and also a fitness guy. But iam not doing any workouts now iam just doing walking. I don't know how it was spread to me, i remember that I touched so many little students on their cheeks and mouths because of their cute words, and at that time so many students got sick with fever. Is it spreaded from my students, When iam teaching iam getting cough but it's neither worse cough nor normal cough it's like moderate to above average level. How can I clear all these problems.