I have been having shoulder and biceps troubles for around 1 year. it seems like a hyper reactive stretch reflex which elicits a rhythmic pulsation.

Need an examination : The long head of the biceps attaches to the top of the shoulder socket (glenoid). Pain in the front of the shoulder (may radiate down the arm);weakness are common symptoms of biceps tendonitis, inflammation of the biceps tendon.It usually happens with other shoulder problems like rotator cuff injury, labrum tears or shoulder instability. Get evaluated by a doc, may need shoulder ultrasound +/- mri.