Reptile & Amphibian Forums

I bought my iguana about 6 months ago and he looked newly born, so I would gauge em at being about 7 months old. He had this vibrant green color that was birghter then well colored grass. Recently, I moved. When I moved, I didnt know where to get some greens for him, so I fed him some of my back up iguana food made by rep-cal. The "growth formula juvenile iguana food". Whithin about two weeks of doing all of this, his color started to fade severely. As of how, his tail looks kinda of pail, and the top of his body is turning from bright green do black. The belly of his body looks as green as it used to, but everywhere the UVB hits on him is turning black. He is eating normally, and I put him back on his old food with calcium dust. He has a good basking spot, and is still energetic. His fecal matter looks the same as it used to, and he is still going regularly. He doesnt seem to have any less energy, and his eyes are still the same color. He sleeps a little bit more durring the day then I remember, but that could be just my noticing it since I am closer to his cage now, as it is next to my computer.
So, I am wondering, what could be causing his color to fade so fast, what can I do to get his color back, and how to know if my UVB is still permitting the right types of light. He rencently shed, and looked rather pale for a while before that, but his color hasnt returned to normal even after he shed. I do not know what to do, or even if it is possible to get that pretty green color back. Any kind of help is much appreciated. Thank you in advance. I will attempt to post pictures if I can find a camera.

I forgot to mention I also moved him to a new tank, a 40 gallon cage.