Coming up on six months with the problem. Everyday is a struggle. A few things I've noticed along the way:
Taking a break midway through the run for water, bathroom, stretch, etc allows whatever stress is being put on my leg to relieve itsself and regain mobility, coordination and feeling when I start back up. For example if I'm running 10 miles- I run five miles, stop for 30 seconds to go to the bathroom and whatnot, then begin running again and in this case I'm usually able to complete the run without much problem. If, however, I tried to run 10 miles straight without a short stop I would most likely begin to lose coordination at mile 7 or 8.
So based off that I'm able to run anywhere from 6-8 miles at 7:00/mile before the loss of coordination sets in (depending on the day).
Other things I noticed that trigger a loss of coordination sooner are running faster and progressively decreasing the pace. I used to run the majority of my easy runs at 7:00/mile but towards the end if I felt good I liked to progressively decrease the pace the last few miles. Going along the lines of 6:30, 6:15, 6:00. I can no longer do this as it would definitely trigger a loss of coordination much sooner.
Ontop of all this I'm currently working a job I hate, have lost my girlfriend, and am studying a program in grad school that I have no interest in. Running was the one thing that kept me sane. Last summer I got pretty low (depressed) and took my frusterations and sadness out in training. I ramped up to 100mpw and kept it there for months without rest. I got in great shape and was starting to feel a bit betterr. Then this nightmare of a problem occurred and I haven't been the same since.
I would love to return to full strength and put this coordination problem behind me one day. All responses on here are just so unpromising as to what could possibly help someone such as ourselves get over this problem.
Please, anyone help.