你的句子的确有误，尽管前后两句的主语不一致，但谓语也不一致，所以前句应该改为Not only does May like painting...。当not only...but also连接两个句子时，如果not only位于句首，则not only后的句子应该用部分倒装。葛传槼《英语惯用法词典》（2012修订版P.396）就有说明：
18.注意下面两句里用is he和will the story，不用he is和the story will：
Not only is he deeply interested in the subject but (also) all his brothers study it night and day.
Not only will the story prove interesting to us but (also) its English will help us in compositions.
▲不过也有not only位于句首谓语不倒装的情况。如果前后两句的主语不一致，但谓语一致，则可以不倒装，前提是后句必须省略与前句相同的谓语。例如：
Not only the bathroom was flooded, but also the rest of the house.不仅浴室里都是水，而且房子里的其他地方也全是水。《牛津英语用法指南》
Not only the grandparents were there but also the aunts, uncles and cousins. 不光是祖父母，连姑母、叔父及其子女也在那里。《牛津高阶英汉双解词典》
既然后句省略了与前句相同的谓语，那么后句的主语可作为前句的并列主语。以上两句话可改为：
Not only the bathroom but also the rest of the house was flooded.
Not only the grandparents but also the aunts, uncles and cousins were there.
