What Causes Squeezing Sensation And Tightness In The Chest?

I am 52 yeas old and had my medical check-up done. I am Hypertensive since 10 years without any family history and it was due to mental stress. I am under medication and my BP is under control. In my recent medica check-up report, everything is normal but during 9 minutes of walk on the treadmill, report showed mildly positive. Cardiologist evaluated my report and asked me did I got any pain or breathing problem during test. Since it was not there, he wrote negetive in the place of positive in the report. Now since last two weeks, I am having tightness, squeezing on my left side of the chest and also tiredness on left hand. Also sometimes I feel imbalance of my body and this is only sometimes even when I am on rest. I do brisk walk and sometimes swimming. During Exercise/brisk walk I do not get any pain or problem in breathing. When see the symptoms in the internet, symptoms are related to heart problem. Please advise