I just made a post about this in open topics (since it is not environmental).
Both my Husband and I get sick from aspartame, usually in the form of terrible headaches and I'd get pretty bad nausea.
Therefore we both have avoided aspartame containing products and for 1-2 years we've been off of it, not drinking diet beverages of any sort.
Then recently (past several months) we've been drinking a low carb diet sports beverage which contains aspartame. We haven't really been getting headaches (the product contains caffeine -- it's sugar free Red Bull) so it replaces any type of caffeine addiction to coca cola for example. But we've both been feeling not quite right, and I've been getting a great deal of cramps which feel like uterine cramps.
These are not the same kind of cramps I get from lower intestine problems or gas, but feel quite similar to period cramps. I'm trying to see if I can figure out what it is or if this is a factor.