So much work usually makes my father(feel)very tired为什么不用feels?

固定用法

make sb do sth

feel 是 my father 的宾语补足语。要用原形。make sb do 结构
例如: The boss made his workers work (原形宾语补足语)all day long.

feels 是动词的第三人称单数，作谓语。
he often feels tired recently.
清楚了吗？

make 作使役性动词，“让”的意思，相当于let，后接动词原形。

一楼和三楼说得很清楚了