I am worried about my father's poor health condition.
I am worried to see my father in a bad health condition.
調子が悪いというのは、
'Poor health condition'
'Bad health condition'
'Bad shape'
とよく使います。
お父さんの調子が最近悪くなって、どうしようか心配なのーI just don't know what to do for my day who has been in a bad shape lately.
調子が悪いの?-Are you alright?/ Are you feeling sick?
といった表現を使って頂ければと思います。
どうぞご参考までに。