Constipation: Given the patient's age and symptoms of nausea, vomiting, and difficulty going to the washroom, constipation is a common issue in the elderly that can cause these symptoms due to fecal impaction or hard stools.

Gastroenteritis: Infection of the stomach and intestines can cause nausea, vomiting, and stomach pain. In the elderly, it can also lead to constipation due to dehydration and electrolyte imbalances.
Medication Side Effects: Many medications can cause gastrointestinal side effects such as nausea, vomiting, and constipation. Given the age of the patient, polypharmacy is a common issue.
Urinary Tract Infection (UTI): While primarily causing urinary symptoms, UTIs in the elderly can present with non-specific symptoms including nausea, vomiting, and abdominal pain.

Bowel Obstruction: Although less common, a bowel obstruction can cause severe abdominal pain, nausea, vomiting, and constipation. It is a surgical emergency and must be considered, especially if the patient has a history of abdominal surgery.
Mesenteric Ischemia: This condition involves insufficient blood flow to the intestines and can cause severe abdominal pain, nausea, and vomiting. It is more common in the elderly and requires prompt diagnosis and treatment.
Appendicitis: While appendicitis is more common in younger populations, it can occur at any age. In the elderly, it may present with atypical symptoms, making diagnosis more challenging.

Gastroparesis: A condition where the stomach takes too long to empty its contents, which can cause nausea, vomiting, and abdominal pain. It is less common but can be seen in the elderly, especially those with diabetes.
Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease and ulcerative colitis can cause chronic inflammation of the gastrointestinal tract, leading to symptoms like abdominal pain, diarrhea (less commonly constipation), and weight loss. While less common in the elderly, new-onset IBD can occur at any age.