It seems like your mother has developed appendicular abscess because she was not operated for appendicitis.
Appendicular abscess is a collection of pus in the appendix that occurs when acute appendicitis is not managed appropriately. This causes extreme pain with swelling into the lower abdomen. There can also be a palpable mass that is felt in the left lower abdomen. Acute appendicitis cannot be treated later than 5 days after the infection, as the infection would have spread to the surrounding structures and intestine. The appendicitis spontaneously burst open and leads to the formation of the appendicular abscess. Appendicular abscess needs careful monitoring and removal which can be done in more than one way.
I would recommend the following-
1)Consult a radiologist and get an ultrasonography of the abdomen. I t will not only help in the diagnosis of the appendicular abscess but also get information on the size, shape, location of the abscess. These information help in deciding the further course of action.
2)The patient has to be started on long term antibiotic like Tab cefepim and Tab. Clindamycin. If she cannot take orally, intravenous treatment has to be started.
3)After intravenous (IV) antibiotic therapy, an interval appendectomy can be performed 4-6 weeks later.
4)Patients with a larger well-defined abscess: After per cutaneous drainage with IV antibiotics are performed, the patient can be discharged with the catheter in place. Interval appendectomy can be performed after the fistula is closed.
5)Adequate parenteral or IV nutrition needs to be given to prevent dehydration.