Aspartame gives me a headache too, and has a terrible metallic taste. If I accidentally take one sip.
Hubby got sick at a friends anniversary party. He finally asked what the punch was. Hawaiin Punch with ginger ale. Hawaiin Punch has Aspartame.
I heard that there is a gene carried by a very small percentage of the population that makes aspartame taste horrible. Makes sense; most of my friends cannot taste the difference between regular and diet pop but the diet pop makes me gag.