Hello Cati,
It has been my experience that most parents and especially moms know when something is wrong with their baby way before anyone else. Trust your instincts!
Often the pediatrician will try some first line treatments such as changing the diet, ruling out other causes of the spit up and vomiting (allergies, intolerances) and rule out other causes for the crying (illness, constipation, etc).
It will be enormously helpful if you keep track of your son's symptoms. I keep a small notebook nearby to write down information such as night waking, spit up, vomiting, burping, coughing after a meal, fussiness, etc.
I also write down info from doctors visits such as height, weight, recommendations, tests and results, etc.
Having this information will help the pediatrician and the gastroenterologist to diagnose and treat the symptoms.
Best wishes,
Jan Gambino
The Reflux Mom