So when she ceased wolfing down her food and didn't want to play "chase the lamb and take it from Steeler", her Mom Karen thought something might be amiss. And something was. Karen's a vet, so she drew blood and found Sophie very anemic; then she x-rayed her and found nodules in/on her spleen. They've probable ruptured and are bleeding, hence the anemia.
So as I write this, Sophie and her mom are on the way to Purdue's Veterinary Teaching Hospital, where Sophie can have the best level of care -- not unlike that which people get... transfusions, expert surgery with a dedicated anesthesiologist, an ICU with 24x7 staffing... the works.
Hopefully the nodules are benign and Sophie can just have her spleen removed and put this behind her. But to make sure... please keep Sophie in your thoughts and send some power of the paw her way.