If you're just talking about dizziness... that's the first symptom I have if I've had something with gluten. A dizzy, disorientation in the head that makes things feel like they're moving (usually rotationally) when they're not. For me, it only lasts 15-30 minutes, and happens 15-30 minutes after I first ingest the offending substance, but it sure ain't fun. (I describe it to friends as something like the feeling of being drunk, without it being funny in any way whatsoever.)
I had this problem pretty much throughout all of my childhood. I was diagnosed with Celaics at age 15 (I'm now 21) and the dizziness has since then stopped, but I used to get that all the time and it never stopped until I was diagnosed. It was awful!!