That’s it basically. How does guilt make you feel like you have been kicked in the stomach? Is it a chemical thing?
It’s kind of simpler and more complex at once. Everything emotional creates physical sensations from chemicals, hormones, muscular actions. We just aren’t very attuned to them but if you pay attention you’ll find that you behave differently in a physical sense when you’re happy or sad.
And guilt is a very strong emotion. Fortunately it’s one of the easiest to deal with. Assuming you are an average slob, and not someone wracked with obsessive guilt, guilty feelings are just telling you that you did something you believe is wrong. All you have to do is contemplate what reparations you will make. If these thoughts make you feel better, carry it out and the guilt is gone.
I would imagine the physical reaction is the same as for stress, you are stressed about not having done something differently, or stressed about the possibility of getting caught.