Irritable Bowel Syndrome (IBS): This is a common condition characterized by chronic abdominal pain, bloating, and alteration of bowel habits. The symptoms of bloating and nausea are typical for IBS, making it the most likely diagnosis.

Gastroesophageal Reflux Disease (GERD): GERD can cause nausea and bloating due to the reflux of stomach acid into the esophagus, leading to discomfort and digestive issues.
Functional Dyspepsia: This condition involves recurring signs and symptoms of indigestion that have no obvious cause. Bloating and nausea are common symptoms.
Lactose Intolerance: The inability to digest lactose can lead to bloating, nausea, and other gastrointestinal symptoms after consuming lactose-containing products.
Food Intolerance: Similar to lactose intolerance, other food intolerances (e.g., gluten, fructose) can cause bloating and nausea.

Appendicitis: Although less common, appendicitis can present with nausea and bloating, especially if the appendix is located near the stomach or intestines. Missing this diagnosis can lead to severe consequences.
Gallbladder Disease: Gallstones or cholecystitis can cause nausea and bloating, particularly after eating fatty foods. These conditions require prompt medical attention.
Pancreatitis: Inflammation of the pancreas can cause severe abdominal pain, nausea, and bloating. It is a medical emergency.
Intestinal Obstruction: A blockage in the intestines can lead to severe bloating, nausea, and vomiting, requiring immediate medical intervention.

Celiac Disease: An autoimmune disorder where the ingestion of gluten leads to damage in the small intestine, causing bloating, nausea, and other symptoms.
Gastroparesis: A condition where the stomach takes too long to empty its contents, leading to nausea, bloating, and other digestive issues.
Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease and ulcerative colitis can cause bloating and nausea, among other symptoms, due to chronic inflammation of the gastrointestinal tract.
Hormonal Imbalances: Certain hormonal conditions, such as polycystic ovary syndrome (PCOS) or thyroid disorders, can lead to bloating and nausea, although these are less direct causes.