Cough With No Mucus, Palpitation. For More Than A Month.

Cough with no mucus, palpitation. For more than a month. Saw a doctor, no problem found in x-ray and EKG. Taking cough medicine.
But I still have cough and palpitation, sometimes speak always triggers cough.
Do not know palpitation triggers cough or vice versa.
What is the problem with me? Should i see a cardiologist for palpitation or go back for a physician again for cough.
Thanks for reply!