What would you like to ask? ill water dragon?

I have had 2 water dragons for about 2 years now. They are kept inteh same cage, fed the same. One is perfectly healthy, the other is terribly ill. The smaller (only slightly smaller) has always had health issues. Every 4-5 months I would have to iso him for a few days. He has always gotten better before but this time he is getting worse.

It starts by him being listless, then he will stop moving areuond and eating all together and just lay with his eyes closed all day. This is when I normally out him in an iso tank, up the heat and baby him. I use a medicine dropper to get him water and vitamins. After a day or so he normally perks right up and is back to normal. I dont have a reptile vet anywhere near me, and I called my old one and he said there is probably nothign they could do anyhow.

I was just wondering if anyon eelse has had this problem or anything similar. I know its not the tank, heating, lighting, since the other one is perfectly fine.