Visceral Gout is deposits of uric acid salts that have built up in an organ. It most frequently affects the kidneys, liver and heart. The deposits continuously irritate the organ, and can ultimately cause the organ to fail. Your lizard will be very apathetic, and will be opening and closing their mouth with discomfort. Their movements will be jerky as well.
If your lizard is a herbivore, it may be caused by animal protein being digested.
Your lizard is not getting enough water, and is being dehydrated.
If your lizard was sick, and had to have antibiotics, the antibiotics may be having negative effects.
There is no treatment known.