Now just to be the Devil's Advocate here, I'll mention that migraines themselves can play their own non-paranormal havoc. Aura migraines can cause both auditory and visual hallucinations. Author Lewis Carroll is said to have suffered severe migraines, and characters such as the cheshire cat come from the classic hook visual.
I'm a sensitive. But I'm also highly affected by EMF. High amounts of electric just send my body haywire.
Now having said all that, if there's something really negative in the room (be it a person or an angry spirit), I get a pressure in my head that will eventually turn into a migraine.
If I already have a migraine going into it though, often times I'll have to back out of an investigation just so any aura side effects don't skew my perspective and the final results.