The fact it happens after you have been lying down
is why I believe Betty thinks it could be heartburn. Acid reflux is notorious for rearing its ugly head when
you have been lying flat, which is why they advise you not to eat 2-3 hours before bedtime and to elevate/put a wedge under the head of your bed and not to eat spicy, fried, fatty, citrus, and dairy foods when
you have gastroesophageal reflux disease (GERD).
Please go and get examined in person by a qualified physician!