What Causes Numbness In Left Arm And Pain In Left Shoulder And Chest?

I'm 34..and have numbness on my left arm and sometimes the pain radiates to my left shoulder..In some occasions , I felt nausea , lightheadedness and have shortness of breath as well..My palms and feet gets clammy and cold too..during these period , I have problems cpncentrating and quite confuse..I went to the doctor last year and the ECG test was abnormal..they install the holter and found that there was some "absent" in the report - palpitations..( the doctor didn't explain much but said it was normal ) for woman my age..to have ANXIETY...so they prescribed me with Propanolol at first and last few months change to Metropolol instead ...Since they explained that it was normal and nothing to worried about , so I just thought everything is ok...but then I realised , I often have these symptoms now and start to wonder could it be gastric problems ? There are few occasions , I woke up in the middle of the night because of the squeezing pain I felt in my chest..but it only last few seconds..Is this normal ? Please advise me....