What is unpleasant to bear is seldom offset by the ease of its description. Dermal detachment is a case in point. The sensation of near-spontaneous dermal detachment makes the experience quite memorable, and as most will know, what is painful, unwelcome, or alarming is quite unforgettable and for that reason straightforward to describe.
There are essentially two sensations, one for each form of detachment.
Let's begin by describing the more common sensation. This occurs when skin is lost from small areas that are rubbing against an object or surface. On a shod foot, for example, this might be the area around the heel. At first, the sensation is like that of small stones or gravel in your shoe. (When I was a very young child, my parents would pretend to empty my shoes of intrusive stones - probably in the hope that doing so would delay my realisation that this problem was permanent and unpreventable.) If the friction continues, the effected area enlarges and the gravel seems to sharpen. Swelling occurs too, when the top layers of skin split and roll aside, exposing much rawer, deeper, wetter, pinker tissue to the friction. At this point, the sensation is like that of pressing a pointed object into open flesh that has lost a substantial scab.
The less common sensation occurs with a less common but just as unpleasant form of skin loss. This occurs when large (think palm-sized) areas of skin detach as a result of awkward foot or hand placement. If, as a child, you ever wore shoes that were too large and attempted to walk in them, you will have noticed that your feet travelled inside the shoes. The shoes flopped about as your feet slipped around inside them. Somebody with EB Simplex gets a similar sensation, only the foot is moving inside its skin. The skin loosens, often suddenly, and the foot continues to move, tearing the skin away. There is less pain than in the first form of skin loss that I described and fewer layers lift away, but the suddenness is alarming and the feeling of your body moving away from its housing is quite nauseating.
The skin grows back over three days. The second day is when the exposed, raw tissue is the most sensitive to contact. On the third day, the area begins to dry and harden slightly.
Any area of the body can be effected, but for the sake of description, I use the example of feet. Most people can relate to the discomfort of poorly fitting footwear. After the feet, the hands are typically the most affected area. Any repetitive, manual effort will cause separation of the skin at the point of most contact. EB Simplex sufferers never develop skin callouses, because the callouses require layers of skin to grow and build up in response to friction. The EB response to friction is loss of skin. When I was a kid, riding a bike would cause skin loss around the webbish thumb-to-forefinger area of the hand and the pads between finger roots and palm.