Thanks for posting your query.
With the available described symptoms, there could be possibility of acute viral gastroenteritis
Presence of loose diarrhea
and weakness suggests the diagnosis.
You should consult with internal medicine specialist/ general surgeon
and should go for thorough check up.
You should also go for complete blood count
imaging, and serum electrolytes.
You should take complete antibiotic therapy, antispasmodics, probiotics, antipyretics, if needed.
You should maintain your hydration by taking potassium rich liquids.
Frequent loose diarrhea may cause loss of potassium with weakness and fatigue feeling.
Avoid milk and all milk related products.
Dr. Mayank Bhargava