My doctor told me ultrasounds are not conclusive for gall stones.
If you were recently pregnant that can push the stones further along down the duct and cause pain.
My mother had that happen right after she had me, and nearly died because the stones suddenly caused a blockage and she had no idea what she had.
Surgery in those days was brutal and she had a scar from top to bottom but thank God she lived.
Today they would have caught it a lot sooner and they remove the stones with a laproscope so it's not major surgery.