My left arm, shoulder and upper left back hurts and my arm feels numbed and tingling for about 5 days. I was pulling a shopping cart for a couple of hours from the front part with my left hand because my uncle is blind so he pushes the cart while a pulled it front the front to direct him. Do you think that could be a reason for these symptoms?
Yes you are suspecting right .please visit an orthopedic surgeon he will evaluate whether do you have any tendon or muscle tear.he may order X-ray or shoulder MRI