○ Don't hesitate to ask for help. 助けが必要なら言って下さい。
hesitate (口ごもるが原義) ためらう躊躇する
○ Please don't trouble yourself. どうぞお構いなく。
trouble 人に迷惑をかける、手数をかけさせる、面倒をかける。
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I'm suffering from a headache, so I want to lie.
Don't hesitate to ask for help.
It's very kind of you, but you are so busy now, please don't trouble yourself, I'll be well soon.