Worried about my White's Dumpy :(

[rachel]

I have two white's tree frogs. I am concerned about one of them right now though. He has a large lump on his back. I am not sure if this has to do with his intestines or not. He is being active as normal and still trying to interact with me but I am worried that he is sick or in pain. Anyone have an idea of what could be wrong? He or she is approximately 7 months old

Here is a picture of his current state. The water looks dirty, I know. I had to find out the hard way that a certain brand of moss will dye the water jacuzzi green and i refuse to bleach it.

Please help. I'm so worried about Jesús. I think his tank buddy Jorge is worried also