I am sure that different people react differently to all sorts of foods. My awareness has been heightened recently due to diabetes, and I noticed that when I started eating premade Splenda sweetened jello cups and Splenda flavor (which I used in water and plain Greek yogurt) I got some symptoms and when I stopped the symptoms went away.
This is not to label Splenda a bad guy, because reactions can be individual. It is more of a wakeup call to myself to pay attention to things that change when one makes a food change; to experiment to see if that change always shows up in similar circumstances, and to decide what to do. For now, no artificial sweeteners. The jello cups got dumped.