My steppe runner, who I got as an adult and have had for a few years, has suddenly become very weak, lethargic, and has lost a lot of weight. His tank conditions are correct and the same as they have always been. He used to be very active and a very wild eater, now he does not run away when I put my hand in the cage and he has to be fed by hand. This has been happening for a few days now and he is getting worse by the day. Please tell me of any ideas you have for what may be happening and how I could bring him back to health. Thanks. I will post pictures soon.