Gastroparesis: This condition is characterized by delayed gastric emptying, leading to symptoms such as vomiting, especially after eating solid foods, and weight loss. The absence of other concerning symptoms and unremarkable lab tests makes this a plausible diagnosis, as gastroparesis can be primary (idiopathic) or secondary to other conditions like diabetes, but the latter would likely show some abnormality in the CMP.

Functional Dyspepsia: This condition involves recurring signs and symptoms of indigestion that have no obvious cause. Symptoms can include vomiting, especially after eating, and weight loss due to reduced food intake. It's a common condition that could fit the patient's presentation.
Peptic Ulcer Disease: Although the patient does not have other concerning symptoms like abdominal pain, peptic ulcers can sometimes present atypically, especially in older adults. Vomiting and weight loss can occur, especially if the ulcer causes a gastric outlet obstruction.
Gastroesophageal Reflux Disease (GERD): While more commonly associated with heartburn, severe GERD can lead to dysphagia and vomiting, particularly of solid foods, due to esophageal irritation or stricture formation.

Esophageal Cancer: Although less likely due to the relatively short duration of symptoms and lack of other alarming features like dysphagia to solids and liquids or significant anemia, esophageal cancer must be considered due to its poor prognosis if missed.
Gastric Cancer: Similar to esophageal cancer, gastric cancer is a critical diagnosis not to miss. Early symptoms can be nonspecific, including weight loss and vomiting, especially if the tumor obstructs the gastric outlet.
Pancreatic Cancer: Despite normal pancreatic enzymes, pancreatic cancer, especially in the body or tail of the pancreas, might not always present with abnormal lab tests initially. Weight loss and vomiting can be early symptoms, especially if there's gastric outlet obstruction.

Eosinophilic Esophagitis: This condition, characterized by an eosinophil-predominant inflammation of the esophagus, can cause dysphagia and food impaction, leading to vomiting and weight loss. It's more common in younger individuals but should be considered in the differential for atypical presentations.
Rumination Syndrome: A condition where food is regurgitated and then chewed and swallowed again, which can lead to weight loss and vomiting. It's more common in individuals with intellectual disabilities but can occur in anyone.
Superior Mesenteric Artery Syndrome: A rare condition caused by compression of the duodenum between the abdominal aorta and the superior mesenteric artery, leading to vomiting and weight loss. It's often associated with significant weight loss and dehydration.