No worries about the skin coming off at the top of the hoof. It's just the periople: It is a thin skin that covers where the coronary band and hoof wall join. It's just like the cuticle on your nails. In wet weather it swells up and turns whiter, and sometimes it peels off. You know how sometimes your cuticles peel off when they get extra soft? Same thing.
But the lameness and swelling is another issue. Your horse could have an abscess brewing, be fighting scratches that are hiding under the hair around the pastern, or some other issue. Your hoof has some bad flares on the sides so hopefully your farrier can address those too.