How to tell difference between carpal and cubital tunnel syndrome? I got elbow pain, tingling in thumb, middle, index and ring, sometimes pinkie

NCV/EMG. Truth be told, there's a lot of symptom overlap amongst the compressive neuropathies of the arm. For example, carpal tunnel syndrome can radiate symptoms up to the shoulder. Your best bet would be getting a nerve conduction velocity with EMG. Technically you could have both issues, and this test can elucidate that as well.