Anxiety can definitely affect your digestive system, and loose stools (diarrhea), an urgent need to go to the bathroom, loss of appetite, and stomach upset are all pretty common side effects of anxiety.
Any time I get a rush of adrenaline or anxiety, or if I feel a panic attack coming on, I immediately feel my stomach ramp up and head to the bathroom. I've also felt nauseated and dizzy because of anxiety.
However, if you are having semi-frequent diarrhea, you should make sure to drink extra water. Dehydration will make you feel even worse, and if you're anxious, you don't want to give yourself any more symptoms to obsess about.
If your stools look different, it could be for a number of reasons. Eating cereal more frequently often means more fiber in your diet, which results in bulkier, more fibrous stools. And if anxiety is affecting your GI system, you may also notice that your stools are lighter in color than usual. This often just means that the stool has passed more quickly than usual through your system and has not had time to stain properly (stool undergoes a process where it turns from greenish yellow to darker brown as it passes through your system). Anxiety can also kill your appetite-- I also have trouble eating when I feel anxious, and food will sometimes make me feel ill or nauseated.
Have you considered treatment for your anxiety? Medication, therapy, and even massage can help mitigate these kinds of symptoms.
At any rate, I wish you the best, and I hope you are able to relax a bit.