CerenaDaft,
If it is turning white INSIDE the body, I strongly think it is the bacterial infection that was mentioned before.
Like others have said, I think your best bet is to remove the shrimp. I would not wait another minute to do this! If it's nothing....you will still have done the best option at this point.
I'll watch for a pic to be posted. That would help us a lot.
Also, if I were you, I would do more like an 80% water change at this point. Doing less than that...I think the chances of the bacteria still being in the tank is high.
Good Luck.