Make sure that the Tums has at least 300 mg of calcium. If you have vitamin D, that can also be given. Will the membrane come out if you gently pull it? Let us know how she gets along.
It is probably another soft egg covered by a membrane. I would gently try to remove it. The other chickens will peck at it if they get the chance. Offer her a human calcium citrate tablet with vitamin D or Tums orally once a day for the next week. Walmart sells the generic for under $9. That may...