Gastroenteritis: This is the most likely diagnosis given the symptoms of multiple yellow bowel movements daily for a week without fever or chills. The yellow color of the stool suggests the presence of bile, which is consistent with an infectious or inflammatory process affecting the gastrointestinal tract.

Irritable Bowel Syndrome (IBS): Although IBS typically presents with a mix of diarrhea and constipation, some patients may experience persistent diarrhea, which could result in frequent yellow bowel movements.
Lactose Intolerance: This condition, characterized by the inability to digest lactose, can lead to diarrhea, bloating, and gas after consuming lactose-containing products. The diarrhea could be yellow if it contains bile.
Giardiasis: An intestinal infection caused by the parasite Giardia lamblia, which can lead to chronic diarrhea, abdominal cramps, and weight loss. The stool may be yellow and greasy.

Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease and ulcerative colitis can cause chronic diarrhea, which may be bloody or contain mucus. Although less common, these conditions can have severe complications if not diagnosed and treated properly.
Celiac Disease: An autoimmune disorder where the ingestion of gluten leads to damage in the small intestine, causing malabsorption and various gastrointestinal symptoms, including diarrhea.
Bacterial Overgrowth (SIBO): A condition where bacteria overgrow in the small intestine, leading to malabsorption, bloating, gas, and diarrhea.

Whipple's Disease: A rare, systemic bacterial infection (Tropheryma whipplei) that can cause malabsorption, weight loss, and diarrhea, among other symptoms.
Short Bowel Syndrome: A condition that results from a significant loss of intestinal tissue, leading to malabsorption and chronic diarrhea.
Pancreatic Insufficiency: A condition where the pancreas does not produce enough digestive enzymes, leading to malabsorption and changes in stool, including diarrhea.