Jennybean,
Why don't you simply take a lactose intolerance test? I took one when I suspected I was lactose intolerant but I wasn't. It was a simple procedure when I took it and I guess it is available in the US as well. The test entailed drinking a large amount of lactose on an empty stomach, 50g I think, and they watched the sugar levels taking frequent blood samples. If your blood sugar does not rise, that indicates absence of lactase (or you not having enough of the enzyme).
You can still have problems with dairy, though, I think that you can be allergic to a protein in milk as well even if it is quite uncommon.
Even if I wasn't lactose intolerant I feel much better not eating lots of dairy. And I ate a lot of dairy before. It causes some indigestion for me in any case.
There are charts you can read to learn the lactose contents of different foods. Hard cheeses are fortunately quite low on lactose compared to milk or cream. Don't know if this applies to camembert or brie, though.
I had a troublesome stomach too but I kept a diary of what I ate for about half a year, cooked most of the food I ate myself, and monitored how I felt simultaneously. It was enough for me to find what was causing my stomach problems. I modified my diet accordingly and now I can almost eat anything I want again barring a few items.