Is it necessary to wash under the fingernails and under the "shaqṣah" (the dead skin hanging beside the nails) during a sufficient ghusl?

The summary of the fatwa (definition) is that the questioner is afflicted with waswasah (obsessive whispering), and its cure is to ignore it. Water must reach beneath the fingernails, and dirt that prevents water from reaching (the skin) must be removed, according to some scholars. As for the "splinter" (or shard/piece), if it is dead skin, it must be removed for the water to reach (the skin). However, if it is live tissue and causes pain upon removal, it suffices to wash over it without removing it.