Biliary Colic or Cholecystitis: The patient's symptoms of right upper quadrant pain radiating to the back, associated with nausea, and occurring once or twice a week, are suggestive of biliary colic or cholecystitis, especially given the absence of other gastrointestinal symptoms like diarrhea or constipation.

Peptic Ulcer Disease: Although the patient does not report black stools, bloody stools, or coffee-ground emesis, peptic ulcer disease could still be a consideration, especially if the pain is related to eating or if she has been taking NSAIDs (not mentioned but possible).
Gastroesophageal Reflux Disease (GERD): GERD could cause upper abdominal pain and nausea, especially if the pain radiates to the back. However, the lack of typical symptoms like heartburn makes this less likely.
Ovarian Cysts: Given the patient still has her ovaries and has had a recent hysterectomy, ovarian cysts could be a cause of lower abdominal pain. The pain pattern does not strongly suggest this, but it remains a possibility.

Pancreatitis: Although the patient's pain pattern and lack of specific risk factors (like gallstones or heavy alcohol use) make this less likely, pancreatitis is a condition that could be deadly if missed. The radiation of pain to the back is a red flag.
Appendicitis: Although the pain is not localized to the right lower quadrant and the patient does not have fever or leukocytosis mentioned, appendicitis can present atypically, especially in adults, and is a diagnosis that should not be missed due to its potential for serious complications.
Hepatic or Renal Pathology: Conditions affecting the liver or kidneys, such as liver abscess, hepatic tumors, or renal stones, could cause the described pain and would be critical to diagnose early.

Inflammatory Bowel Disease (IBD): While IBD (Crohn's disease or ulcerative colitis) could cause abdominal pain and nausea, the lack of changes in bowel habits, blood in stool, or weight loss makes this less likely.
Abdominal Malignancy: Various abdominal malignancies could cause the patient's symptoms, but these would be rare and typically associated with other symptoms like weight loss or more persistent pain.
Adhesions or Bowel Obstruction: Given the patient's history of recent surgery, adhesions causing intermittent bowel obstruction could be a rare but possible cause of her symptoms.