What happens in extreme severe cases where there is too much yeast inside the body ie esophagus,stomach , bloodstream & the body becomes too skinny?

Yeast infections: The scenario you describe sounds like diffuse, systemic fungal infection and this is usually seen in persons who are severely immunocompromised. Yeast in the blood can be life-threatening, yeast in the esophagus and other organs can cause difficulty eating and drinking, malabsorption, weight loss, wasting. It is very serious and requires aggressive treatment of the infection and underlying cause