Miserable!

I thought my knee was going to be my biggest issue-well my back decides to start acting up. I usually don't have too many issues (knock on wood). Usually it will ache some after a long run but now it is bothering me while sitting at work which probably makes it stiffer so I have been trying to get up and stretch. I took almost a week off after the Run Amuck and did 10 yesterday. Not sure if it was a mistake or not. The rest of the group did 17 miles-so now I am feeling behind yet again? From the beginning of the run it was bothering me and part of me was like what am I doing-is it really worth this. I stuck it out to get the 10 miles that I was determined to do but I walked a lot. My feeling is that if I don't feel worse after the run that keep running but I am not so sure. I also wonder if it is mental-am I really feeling this pain-yes! Is it just another excuse in my book of excuses-is this really something I want to do. I really want to run a marathon this year because like last year I am not willing to go through this again. I have gotten so close I feel yet the start line feels so far away. Do I have enough time to get this back issue resolved-I guess we will see...