#1
When I say strange humming noise, I mean a weird humming noise I make when I breath every now and then when playing fast on the guitar, not the guitar itself.

I've been playing for awhile and I want to stop doing this stupid habit when playing , I can never hear myself doing it but I do it anyways at random times when playing. If anyone else has had a problem like this and has stopped it with breathing exercises or anything please let me know.
#2
You are not alone, Grasshopper! If you concentrate on anything to a tremendous degree, you can actually screw with some aspects of your autonomic nervous system a bit. This is very common in people who study meditation: the noobs frequently seem to forget to breathe in the beginning. That "hum" that you make is essentially the autonomic part of your brain kicking you in the ass and saying: "Hey, idiot! Quit ****ing with me! You need to breathe!" Fixing it is probably less about breathing exercises than it is about relaxation exercises. You need to ease up and not focus so intensely, which is what you do when you are playing fast. Practice, and learn your parts slowly. Then add the speed juice, and you will be more comfortable with your playing. Then, you will not need to devote so much of your brain to the task, and you will not have your brain making that audible reminder to breathe.

Stick with it, and try to relax. You will fix the problem. And hey; a hum is a hell of a lot better than blacking out due to a lack of air!
"Maybe this world is another planet's hell?" - Aldous Huxley