If your lizard has a case of intestinal tract inflammation, you will notice a severe decrease in appetite. Along with this, their normal activity, movements and attentiveness will also be decreased. Your lizards feces will be very watery, and will have a very foul smell to them. In some cases, but not all, you may notice the cloaca has a reddish tinge of color to it.
You should examine the fecal matter to rule out parasites and worms. Treatment from a veterinarian should be sought out immediately, as lost time can result in death from starvation.