a millstone round one's neck

1. 套在身上的沉重負擔
   His lazy son is a millstone round his neck.

   他那懶散的兒子是套在他身上的一個沉重負擔。

between the upper and nether millstone

1. 上下受夾攻；備受不可抗拒的壓力
   He's between the upper and nether millstone.

   他深受上下夾攻。