In my experience, "stir up" is not a common "compound noun." "Mix up" is, but doesn't fit your application.
The verb usage is much more common. "He stirred up a whole bunch of crap" (pardon the vernacular). "He really stirred something up when he opened this particular can of worms!" (mixed metaphor)
"He really created a buzz" is acceptable, but I don't think it has the negative connotation you're looking for. Buzzes can be good as well as bad.
- A.