Little pain on left side of chest.

I consulted a doctor nearly 25 days ago from now as I was having a little pain on the upper left side of the chest after doing intense cardio vascular exercises for 1month. My blood pressure was 148/80 and pulse rate was around 80. He gave me some medicines for anxiety issues. I smoke 1-2 ciggerates a day. So I stopped smoking for 20 days, continued my prescribed medications and did some meditation and little yoga. No more intense cardiovascular exercises until now. I was back in my normal healthy state. But I am walking for around 3-4kms a day to stay fit since last week. I am facing some issues with my heart now. Sometimes I feel a little burn on my left side of chest. Sometimes I can hear my heartbeat and feel heavy on this side of chest. Also, I was a state level swimmer for consecutive 4years until 15years of my age (class 11). I suffered from high blood pressure before my boards (12th) which got normal in few days. Please, help me I want to be fit & live my life normally.