Why do I have persistent cough and tightness in my chest after taking Metoprolol?

Hello doctor,

I was prescribed metoprolol six months ago for heart palpitations and I am taking a daily dose of 50mg. During my follow-up appointment six weeks later, I informed my doctor that the medication did not alleviate the palpitations and, in fact, I felt they were occurring more frequently. In response, my doctor increased my dosage to 100 mg per day. Shortly thereafter, I developed a persistent cough. Initially, I assumed it was because I was having a cold, but even after my cold symptoms subsided, the cough persisted. Eight weeks after the dosage increase, I returned to my doctor and mentioned that while the palpitations had become less frequent, the cough remained. My doctor listened to my chest and noted no wheezing but decided to prescribe me Levaquin 500 mg daily for a week. Despite this treatment, the cough did not improve after an additional month. The cough is unproductive and occurs frequently when I speak or exhale, but it does not happen at night while I am asleep. I also experience a slight sensation of heaviness or tightness in my chest. I have no history of asthma or allergies. To manage potential causes, I started taking allergy medicine for post-nasal drip and Omeprazole for acid reflux, but there has been no improvement. I contacted my doctor, suspecting that the beta blocker might be related to the cough. However, he dismissed this possibility and scheduled another appointment for me in two weeks. What are your thoughts on whether the cough could be a side effect of metoprolol?

Kindly help.