Wow. That's nasty. Judging from the pictures, I think its venereal.
But no really, the top screen is likely to be the plastic screen insert being dented inwards to the LCD causing distortions. This can be fixed by getting a replacement shell which comes with the screen insert. Another possibility is moisture. Since you describe that it spreads to your finger when you press it, it should be the former.
As for the bottom, can't really comment much. Heat damage perhaps?
More details please. Did you bring your 3ds to the beach? sauna? natural springs? Anything that might cause something to go wrong with your 3ds?