Having pain in upper left muscle of atm tingling and numbness down to my hand

We can't diagnose online. This could be nothing more than a pinched nerve all the way up to a heart attack. If in doubt, get checked out.

If you have a question about it get to the emergency room. It saved my life, it just might yours.

Possible causes of pain in the upper arm with tingling down to the hand (a rough, non-complete list)
- A disorder of the neck spine resulting in a pinched spinal nerve (arthritis, bulging disc or any other disorder, whiplash injury)
- An artery, vein or nerves trapped between the clavicle and the first rib (thoracic outlet syndrome) due to anatomical abnormalities, injury...
- Injury of the shoulder, upper arm or elbow
- Something growing in the upper arm muscles or bone
- Overuse of the elbow (cubital tunnel syndrome)
- Heart disease
- etc.

Before you go to a doctor, you can write down exact location of the pain and numbness, when the symptoms started, what triggers them, are they worse at night, etc.

Here is a long list of causes of numbness in the arm, hand and fingers, which can help you to describe your symptoms to the doctor better:
Causes of Numbness and Tingling (Paresthesia) in Fingertips (http://www.hxbenefit.com/causes-of-numbness-and-tingling-paresthesia-in-fingertips.html)