Okay... Frog pee generally isn't yellow so idk what that was that you saw. If it happens again, get a picture of it. Also, can you get a pic of your frog from above?
If a frog isn't eating, more often than not it's because something isn't right about its habitat setup. What sort of gauges are you using to measure temperature and humidity? If you don't know the brand name, then what do they look like? Some of them are very inaccurate.