Have you had any antibiotics prior to this? Have you had any mild stomach pain or bloating? C.diff can give you regular stomach upset until it's treated.
Regarding your diet. If you're anxiety is not making you hungry and all you eat is an evening meal then you are essentially fasting and what can happen is when you break the fast, unless you choose your food properly, your meal can literally go out as quick as it went in, it used to happen to me with intermittent fasting. Plus your anxiety will probably be higher around meal times in case you get a dodgy stomach.
One thing to try is to only eat something small and non fatty when breaking a fast then eat more a little later but try and not have high fat food (especially junk food) as you'll be on the loo in minutes!
Try and increase your fibre, you could kick start it with some psyllium husk for several days or so.