Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice.
Noted the history about your 19 year old son and understood your concerns.
My thoughts and suggestions are as below. Pain on the areas your have mentioned namely,Left shoulder blade,
chest pain, left jaw pain and under left breast indicate that you should rush to ER for urgent EKG, and all cardiac evaluation as this can be due to cardiac problems like
heart attack. So rush to the nearest ER with some assistance.
Lightheadedness can be due to the same. Since you have got
acid reflux since 20 years, you need a proper evaluation, Upper GI
Endoscopy and other investigations once the cardiac evaluation is done and is normal.This will give an exact idea why the acid reflux has persisted and may need corrective surgery if there is a symptomatic hiatal hernia.
Hope I have answered your query. Let me know if I can assist you further.