Water/sun damage on my HD TV screen? Please help?

I have a 32' Sony Bravia EX400 and just recently (like literally half an hour ago) I noticed this strange mark on the screen. I don't know how long it's been there but I noticed it whilst I was playing Red Dead Redemption as it is most noticeable against a blue background. So the mark is weird because it kinda looks like water damage where there are heaps of small bubbles and then it's like a rainbow colour as if there was water in there but this is impossible as I have never had water anywhere near my TV. So I thought it might be sun damage so I did a bit of research and now this seems highly unlikely. One thing I should point out is that the mark is not visible when the screen is off do it's definitely some kind of internal problem. Does anyone know what it might be or how I can fix it?