Hope this isn't too late, but overtraining is absolutely a possibility--whether it is diagnosed or not. When your body shuts down like that, you know you are there.
And listening to your body won't protect you. If you train hard enough (which obviously you do), your brain has learned to override any "stop" messages. Then to top it off, your endorphins will make you feel good even while you are over your limit. I think that people who have not experienced this personally cannot understand how driving, intense, and wonderful this experience is. It's also destructive, unfortunately, and the fallout/comedown sucks.
I think your plan to go to see this doc is a good one--good luck to you! I hope you'll post what you learn for others to read and learn.