Intermittent mild localized left bicep pain. Dizziness. No swelling/warmth. Blood clot or nerve? I also have left peck and shoulder/blade pain.

? Cervical Radiculop. Athy. One can see dizziness and radiating pain into the upper shoulder, biceps or radial side of the forearm. The pectoralis muscle receives innervation for most all cervical nerve roots and by your description the most likely level would be c5-6. You should see your doctor for a full exam. I hope this helps.