It does feel like the opposite of munchausen. That’s a great way to explain it. And now she’s diagnosed with something so now there can be more attention to her. Maybe she will need a caregiver too? Seems like the perfect way to get her mother to move back in with them so Liz can do everything for them.
Unless she's growing many arms like an Octopus or something? What can be so urgent that it isn't treatable/manageable on her own?