Muscle trigger points are notorious for confusing doctors and sending strange pain patterns throughout the body and mimicking other conditions.
The most likely culprit for the pain spectrum you describe is a muscle called the serratus anterior. This can develop a trigger point (or make an existing trigger point active) when you need extra breath quickly, for example when you are exercising, including running and swimming. It can also be activated by coughing and habitual tension and hyperventilation when under anxious. It can be treated by massage either professionally by someone who understands trigger points or home therapy. the best home remedy is the find the trigger point which will usually be about 4 inches under the arm pit straight down. It will be tender; very tender is active. You need a hard solid ball between the trigger point and a wall; roll the ball using your weight to massage the spot. Do it several times a day.