A receding gumline can be caused by gingivitis or brushing the wrong way. Improper brushing allows plaque to accumulate by exposing the root surface creating holes, called tubules. When the exposed tubules are stimulated, they trigger pain. All of this is microscopic and looks like Swiss cheese under a microscope. Generally people notice dental hypersensitivity in their 20s.
Dental hypersensitivity is run of the mill.
I think if you don't have sensitivity then you're not alive. One way to prevent dental hypersensitivity is to avoid such extreme foods. Remedies such as covering the root surface can alleviate the pain. Using sensitivity tooth pastes may reduce the pain. Constant pain could indicate a cavity or gum recession.