DO NOT MASSAGE. It is very painful for her now, and there is no way to try to help her without endangering breakage of the "membrane". That is most always fatal. This has been the sad end of several of my dearest old hens--11 and 12 years old. Keep her comfortable as possible, do not let her roost, even if she can, as the drop down in the morning may break the shell less egg. This is a different situation than what is called "impacted egg", which is a normal egg (maybe extra large, maybe not) that is held up just inside the vent--can often be helped by warm sitsbath.
When the soft shelled egg finally passes, she will feel fine again, until the next episode. Even with free choice oystershell and complete feed, green feed added for extra calcium, it is a failure of her system and of the shell gland to "finish" the egg, and there is no treatment. The normal peristalsis is ineffective with the soft shelled egg, and it is very painful to the hen waiting for it to pass. I have greatest sympathy and do know that she may possibly be just fine again--that is the hope! CJR