I am sorry to hear about this concern.
Well, a few separate issues.
First, the lump on her rib cage. Unfortunately, that really could be almost anything. A fatty tumor (lipoma), a cyst, a nodule or some other type of tumor.
The urinating more could be very important. Increased urination (polyuria) can be caused kidney disease, urinary tract infection, diabetes, endocrine disease like Cushing's.
What about the shivering. Any type of shivering, tremoring or shaking can be caused by nausea, pain, or endocrine conditions as well.
With refusing to eat, nausea is a very real concern.