Greetings and welcome to justanswer,
What is the exact location of this tightness?
how long are you having?
do you suffer from diabetes or hypertension?
did you consult a doctor yet?
Is it effecting both arms?
any associated chest pain, discomfort, difficulty in breathing, injury?
Thank you for the information,
There are some common causes of such symptoms.The common ones are unstable angina, myocardial infarction, arthritis, nerve irritation, injury, etc.
As per the symptoms you should first rule out the cardiac cause of such symptoms which is commonly assiciated with such tightness and difficulty in breathing along with numbness and tingling in the left arm, shoulder, jaw sometimes.
It is likley to be related to the cardiac cause and you should rule it out by having the relevant investigations done like ekg, 2d echo of heart, exercise treadmill test after consulting a doctor.
The treatment depends on the underlying cause.You may take the aspirin for the control of symptoms and consult a cardiuologist as soon as possible.The other causes should also be ruled out though the chances are less.
Let me know if you have any doubt.