30/m non smoker. have pain on left side neck, left front deltoid that radiates down the inner arm into my ring and pinky finger for the past 2 days. the pain is not severe but irritating. im really scared this is a pancoast tumor. advice?

The most common cause is cervical radiculopathy due to cervical spondylosis. This condition is often self-limited and resolved in a couple days but it can recur. You can prevent the recurrence by neck and back exercise. Changing your pillow and using firm mattress may be useful. You are not at risk for lung cancer so I wonder why you think about that worst condition. Take care.

Not clear why you are focusing on lung cancer, but you should first see your doctor and get examined. Your description is most consistent with a pinched nerve in your neck or shoulder. This could indeed be thoracic outlet syndrome. A properly performed EMG study might well be quite revealing.