Annie May was the second daughter born to my great grand Uncle Andrew/Andy & his wife Callie.
Annie only lived 3 months before she died of stenosis (narrowing) of the stomach.
According to the Mayo clinic.org website, this condition is rare, only effecting 2 to 4 out of 1,000 babies. It causes babies to vomit forcefully, leaving baby constantly hungry.
Today, this condition is fixed with surgery, unfortunately for little Annie, she died in 1921. If she even saw a doctor for this condition, the technology to determine if that was the problem, was not available yet, so they may not have even found it.(According to Wikipedia, diagnosis for pyloric stenosis is accomplished with an Upper GI (gastrointestinal series) & abdominal ultrasound. The first UGI wasn't done until the 60's & the first ultrasound in the late 40's)