Something isn’t right. Something feels wrong.

Of course. Always. There is always another way to say it. . Something feels off. Something does not feel right (here). Something about this feels off. Something about this feels wrong. Something about this does not feel right. Something's off. I have a bad feeling about this. My spider sense is tingling. . similar This seems too good to be true. . Also, as you have written it, or said, it, we must assume an intention to warn someone. So there are many ways to warn. .

Something is fishy. I (highly) doubt that.