I'm 36 years old diabetic man having cough problems 3-4 times a year. It starts with sore throat and continue with heavy cough and didn't get running nose. Every time I used to take a prescription of antibiotics plus erthryomicin. Now this is too effective. It seems all cough is sticked inside me. Very low amounts of cough comes outside. Tell me any effective medicine course to come out of this problem.