The phrenic nerve is a nerve that originates in the neck, passes down between
the lung and heart, to reach the diaphragm, the main breathing muscle. It is
important for breathing, as it passes motor information to the diaphragm and
receives sensory information from it. It is also responsible for nerves
that transmit sensory messages to the brain from the pericardium
(the tissue that surrounds the heart), pleura (the tissue that covers the
lungs), and the lungs.

Any irritation to this nerve produces what we call referred
pain above the collar bone and over the chest, just like the pricking sensation
you are describing, or pain in the shoulder as well. Irritation to the
diaphragm could result from transient events like abdominal distention.