Why is my keyboard acting so strangely?

Hi all,

I'm having a very odd problem with my keyboard on my Macbook Pro Retina Early 2013.

The best way I can describe the problem is that a bulk majority of the keys do not work or respond. However, after giving the computer 5-10 minutes the keys gradually become completely functional. While there are some letters/glyphs that occasionally give me trouble during the first few minutes, they are not confined to a certain area within the keyboard and the problematic keys are never the same.

Any thoughts what could be going on? There's been no accidental damage to the machine and unfortunately I'm about three months out of warranty. Any thoughts on why it might be doing this? It's quite strange.

To give a better idea of the problem, here is an image of me trying to type the same few short sentences over and over again while the computer begins to work again. First sentence is the sentence I'm typing, free of errors.