This short video from Terry talks about what to do if you can't find the trigger points causing your arm pain. 

A Trigger Point (TrP) is a hyperirritable, or especially tender or sore, spot in the bands of skeletal muscles' fascia. When a trigger point is chronic, it can lead to Myofascial Pain Syndrome.  Muscle injury or muscle stress from repetitive motions can lead to the development of trigger points. The great news is that when you do locate the trigger point, arm massage and trigger point therapy can help lessen the arm pain you are feeling.

An odd characteristic of these spots is they often elicit arm pain distant from the actual trigger point.  This can make them difficult to locate, because while you may naturally focus on the painful area for treatment, that isn't necessarily where the problem is.  You'll need to work carefully and patiently along your arm to find your trigger points. After doing this focused attention several times, if you are unable to find trigger points in your arms and hands, you may have a different medical condition.