Can you post a good picture of the frog? The side that is see through if you can get it. I don't think its your setup, it looks fine. When you look at the see through part does it look like there is water in there? What does it feel like when you touch it, does it feel solid on that side or does it feel squishy? Are you sure it wasn't shed in the water? If it wasn't shed he could have some kind of bacterial or fungal infection. Does he seem slimey all the time? Im not sure what the black inside could be but it sounds like your frog retaining water for reason and there could be a few reasons for this. A good picture would be great so we can help you out abit more. Are you still using that analog 2-1 that's on your back wall? Get some digital if you are that thing is no good.