pyloric stenosis

A three-month-old baby boy comes into your clinic with the main complaint that he frequently vomits after eating. He often has a swollen upper belly after feeding and acts fussy all the time. According to his parents, the vomiting has become more frequent this past week and he is beginning to lose weight. After careful history taking, a thorough physical exam and diagnostic work-up, the patient is diagnosed with pyloric stenosis.

What is the etiology of pyloric stenosis?
Describe in detail the pathophysiological process of pyloric stenosis.
Identify hallmark signs identified from the physical exam and presenting symptoms. What diagnostic tests would help to confirm the diagnosis of pyloric stenosis?
Describe the pathophysiology of complications of pyloric stenosis.
What teaching would you provide this patient/parents regarding pyloric stenosis?
references should be 5yrs or less