My aunt, whose ancestry is all Manchester, uses "mither" quite a bit. "I'm not mithered about it".
Late 17th century, unknown origin, possibly Welsh moedrodd to worry or bother. Possible alternative from the Welsh meidda (“‘to beg for whey’”) or perhaps meiddio (“‘to dare or venture’”). Bear in mind that the "dd" in Welsh corresponds in sound to the "th" in mither.
* IPA: /ˈmaɪθər/, SAMPA: /"maIT@r/
Third person singular
to mither (third-person singular simple present mithers, present participle mithering, simple past and past participle mithered)
1. (intransitive, Northern England) To make an unnecessary fuss, moan.
2. (transitive) To pester or irritate someone. Usually directed at children.
"Will you stop mithering me!"