Kids don't eat when they feel a bit ill. My youngest didn't eat a single thing for 11 days about 18 months ago as he had a nasty bug, I even called 111 who weren't concerned at all. They said as long as he's drinking fluids, let it pass.
Remember, you're creating the issue here, not him. Focus on you, not him. Don't over analyse his toilet or eating habits, just walk away and do something else.