HillLee that Ishiguro book is about clones used for organ transplants, so I don't think you need worry too much. It's a rip off of Michael Marshall Smith's Spares, only set in an alternate present rather than an unlikely future...
It sounds to me as if you're not running regularly enough to keep up 8mph for any great distance. I'd try running slower and building up, find a goal and get a training plan. Loads available on google.
Your diet, by the way, sounds a bit rubbish. You're really setting yourself up for peaks and troughs in your energy levels. In the grand scheme of things it isn't THAT bad and it won't kill you, but it's a long way off optimum for a runner.
But I'm guessing that your existing conditions might make diet changes more difficult. (That's a question, really).