My shingles blisters are still here, after a month. I took antivirals-why won't they go away? What's wrong?

Skin damage. It is likely the infection has cleared with the anti-virals, but the damage to the skin can take months to heal. It's not unlike a burn - the skin has to regenerate and create new skin cells, and these areas can be extra sensitive for weeks to months. Think of it in terms of a broken bone - often takes 6-8 weeks to make that new bone after a fracture. Same for skin to heal.