My 5 Year Old Son Has Been Coughing For The

My 5 year old son has been coughing for the last two months now. He has taken antibiotics in the third week. He's taking cough medicines, Claritin everyday and albuterol as needed for wheezing. We have seen his doctor three times already. No blood test were done, nor chest X-rays taken or any diagnostic test. How come his cough won't go away? What should I do next?