Thanks for writing yyour query.
Afer reading your post, it seems that your chest pain
is related to increased acid and gas produuction in your stomach.
You can take antacid
20 mg once a day before breakfast along with Domperidone
Also follow some precautions like :-
1. Avoid spicy/oily foods.
2. Donot miss a meal.
3. Avoid cigarette/alcohol, if any.
4. Avoid emotional/mental stress.
5. Donot self medicate especially with pain killers and steroids
6. Drink atleast 8-10 glasses of water daily.
If the problem persists, get yourself examined and investigated clinically.
When you sleep with your left arm under your head, it results in temporary obstruction of the blood flow and nerve compression, resulting in arm sleeping. It is a normal phenomenon and should not be worried about.
I hope this is helpful to you.