I’m afraid I don’t have much of an answer for you. You are planning on selling her, but a big lump won’t make her very attractive to a potential buyer. A vet bill could easily be more than she’s worth. So you are kinda between a rock and a hard place. If it were me, I’d let her raise the lamb, then slaughter her to feed the family. She would make good pot pie, roast, chili, stew, lamb burgers. Save the organs, including tongue, to feed the dogs. Honor her life by utilizing all you can.
It may sound corny, but when I slaughter an animal, I pray over it, thanking the animal for its life and giving nourishment to my family. I thank God for the good food and for making me a farmer.