Barefeet walking gives one's feet a sturdy massage. Doing so it can, according to my experience, loosen up all kind of things. In foot reflexology, different zones on the sole of the feet are related to corresponding organs. Walking barefeet for first times could present some discomfort or change in the body. But that is a good sign. It could mean that for too long the body has not been manipulated in that way. Having a headache as a result of barefoot walking can be a sign. A sign that some form of stagnation present in your feet or any related organs is being released.
I do wonder how big the benefit of bare feet walking has on my health.