update... tried again and completed!
I was quite disappointed I had to finish earlier today. It got to 6pm, I fed the cat and dog, we then sat down and had our dinner. at 7pm we sat down to watch the dog whisperer and I thought I will have another go, so I went upstairs and swapped my trainers again (pair no.3), set up my ipad next to my treadmill and pressed start.
This time I set the walking speed to 2.5mph and when it got to the running mode, left it at the same speed but I jogged on my toes as if I was skipping across water! and I completed it and most importantly without any pain.