Thanks for using Petco Pet Education Center, formerly Petcoach. I'm sorry to hear Nino isn't feeling well. Based on what you are describing, I would recommend having Nino evaluated by a veterinarian as soon as possible. Extreme lethargy in a cat can be due to a variety of reasons (infection, pain, urinary obstruction, GI issues, etc) and the underlying cause for what you are seeing would need to be identified in order to get him feeling better. Good luck!