Maroon Clown discoloration

[FlashJordan]

My female Maroon clown is showing a splotchy, light discoloration on her underbelly and I'm trying to figure out the cause. Aside from a small cleaner goby, she and her mate are the only fish in the tank. She's almost 3 yrs old, and I've had her the entire time. I've recently put them into a new, larger tank (120g) that is 4 months old with all paramaters in order. Since the introduction to the new tank, she's become extremely aggressive and territorial, biting my hand whenever I'm in the tank to work. She has also been swishing her tail in the sand to move it around while hosting a large brain coral. Is there any nutrient deficiency that could cause this, any disease? It may be something as simple as she's rubbing herself on the bottom too much, but when I look closely it doesn't look like the spots are sores, merely lighter in color.

Here are the pics. Thanks for taking a look!

http://i.imgur.com/MtqhKXk.jpg