Toprol-XL and oral contraceptives

Back in July I was experiencing rapid heart beats and shortness of breath. I'm a 43 white female with a high stress job. I went to the doctor expecting him to prescribe a sedative. He hooked me up to an EKG which showed I had a left bundle branch block. He then ordered blood work, chest x-rays, an ultra sound, and a nuclear stress test. All test came back fine, but my stress test showed a heart attack, which apparently is common with the left bundle block. I then wore a 24 hour Holter moniter which indicated tachycardia. That's when the doctor prescribed 50 mg Metoprolol. My BP and heart rate are now almost normal and the shortness of breath has gone away. I still experience a mild heaviness in my chest, but that is only when I allow my self to be stressed. I have gained over 5 pounds in less than 2 months and my dreams are more vivid than usual. One side effect that was listed on my drug info sheet that I haven't read about on this site described a cough, which I have had for over a month. I mentioned the cough to my doctor and he said it was prob post nasal drip so he prescribed 180 mg Fexofenadine and told me to cut the Metoprolol in half so I would be taking 25 mg. The Fexofenadine has helped with sneezing that I have always experienced, but the cough is still there. The cough is not always severe, but it has interrupted my sleep twice and my job once. The last bad coughing episode lasted 90 mins during the night. Has anyone else experienced the coughing side effect of Metoprolol?