Hamstring/ Glutes

I pulled my hamstring on New Year's Day whilst training for my first ultra-marathon (32 miles), which takes place in Anglesey in 3 days time. I have had a physio look at it and he has said it is a slight pull and has manipulated the problem area. I have since been slightly stretching it and have managed a 2 mile jog yesterday and 3 mile jog today. I do not feel any pain, just achiness in my hamstring when I run, but it eases once I've stretched it off. I do feel slight twinges in my glutes though. The ultra I've been training for is round the corner, and mainly off road, and I am wondering if I would be a fool to have a crack at it. I have been training for months so know I have the stamina and miles on the clock, even though I have had the last 2 weeks off any form of exercise. I am having a sports massage tomorrow and some KT tape applied too. I'm just fighting withmy conscience now!! Has anyone else made the silly decision I'm tempted to make and not regretted it afterwards by making matters worse?