Too much exercise?

I signed up for a 5k and thought it would be a great way to stay motivated to run even though it has become increasingly harder. I know that my health has declined so much since my last run that I would not be able to keep pace with anyone on my team, and I was okay with that. I set a goal just to finish. I would not try to beat my time from last year, which was a hard decision because I am very competitive by nature. But I had to face that fact that my body would not allow me to do that anyway. So I  took it as s lesson in acceptance, and patience. Just finish. So I had been training to just finish, not excel. My run was Saturday. I did better than I thought I would. I was only 2 minutes behind my last time. But inside I still had some resentment and disappointment that my body is not in the same condition it was 10 years ago, or even last year for that matter. Then upon coming home it became harder and harder to walk as the day went on. The back pain, and pain from a pulled shoulder muscle nearly crippled me and I spent the rest of the day on the couch with heat patches and pain pills. Now I am struggling with the question that maybe running is not for me at all, or did I just push myself to hard during this one instance? I am trying to accept things and live each day the best I can, but the mental game is getting old. Guilt, disappointment, embarrassment, feeling like I cannot fully open up about this condition.Wanting to cry but not wanting to seem weak. Wanting to complain without whining, wanting to be strong and feeling like a fragile piece of glass. Days I'm optimistic and feel good I have hope and feel conflicted admitting I have anything wrong at all. But I ran. I raised a lot of money for a non profit organization, and my family is proud of me..but I am still struggling to be proud of myself. I am wondering if any of this goes away, or if continues on like my pain, and I just have to deal.