thank you for your query.
If the clinical examination by 4 doctors in addition to a breast ultrasound
is normal, then you are most probably not having any breast condition to worry about.
An abdominal or gastrointestinal condition can cause referred pain
to the lower ribcage.
However, pain in the upper outer region is not explained by your GI scopy findings too.
It could be a muscular pain
in the abdominal muscles or a pain in the underlying ribs and bony cage.
You could try consulting an orthopedic surgeon as it sounds like more of a muscular pain.