You might think it’s “just a rash,” but fluid-filled blisters are the mildest of symptoms that can include debilitating, never-ending pain. — Dr. Bill Nichols, a friend of mine, recently went through a horrible, preventable ordeal, suffering a severe case of shingles that left him wishing he had gotten the shingles vaccine. “Anytime I have an opportunity, I tell people to get the Shingrix shot,” Nichols said. “I’ve survived therapy for three…