A specialized neuron ending that detects changes in pressure in the skin is functioning as:

Mechanoreceptor

Explanation:

Mechanoreceptors are specialized nerve endings that responds to mechanical pressure, stress, strain or distortion. They are modified into different various forms; we have some that responds to filthy light touch (tactile in nature), some tension deep in the skin (bulbous corpuscles), some rapid vibrations (lamellar corpuscles are pressure receptors located on the skin).