Brief Answer:
probably due to anxiety.

Detailed Answer:
Hello
Welcome here.

Dear XXXXXXX I have gone through your details thoroughly and understand your concerns.

You are facing the problem of increased heart rate and pricking pain in chest.
All your cardiac tests have come out to be normal.

Sorry to hear about the sad demise of your mother.

I would like to tell you that anxiety disorders are usually the diagnosis of exclusion.
As your tests are normal, you need not worry about heart problems.

Anxiety can cause number of symptoms like breathlessness, chest pain, tremors, dizziness, dry mouth, numbness etc.

I think i would agree with your cardiologist that you probably have anxiety.

Your pain and heart rate increase during morning walk or running. This is during to sympathetic hyperactivity in the body.

I would advise you to practice slow and deep breathing and meditation.

Other than this, antianxiety drugs like escitalopram taken on regular basis can help to a great extent. Clonazepam or alprazolam can be taken if anxiety is intense.

You can consult a psychiatrist and discuss about these drugs as these are prescription drugs. Also, psychological therapy like biofeedback will be helpful.

The more you will worry about heart conditions, the more worse pain will get.

Try to stay calm.

Hope this helps.

Feel free to ask further.
Thanks.

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