That looks like shedding to me. That's a normal part of a turtle's growth. My turtles shed a lot after i first rescued them. I'm not sure if it has something also to do with a drastic change in water conditions, but it's nothing to be worried about. What is the temperature of the water? If the temps are on the high side the turtle will shed more often.
Please read through the
http://www.redearslider.com/index_basic_care.html section on this website. Also take a look at the other guides on there about habitat and nutrition. There's a lot of very good information there on how to properly care of your turtle.
A couple of things I noticed from your pictures is the water needs to be deeper as all aquatic turtles are excellent swimmers and prefer to have a lot of room to swim. Also, gravel is deadly to turtles since they can eat them and become impacted. A lot of people have had their turtles suffer and die because of this. Xrays showed the turtle's stomachs completely full of gravel and they were unable to pass them. The gravel also traps a lot of waste and will become like a cesspool.