When Is It Injury vs. When Is It Slight Pain

Playing off of the title, "Pain Now, Wine Later" I am curious about what makes a difference between a slight annoyance when running and other pains felt while in your shoes (and out). I have been battling what I believe is a tendinitis issue in my left ankle for the last couple months. It typically makes me aware of its presence when I'm running, but some days it's worse than others, usually the day after a longer run. For example, this morning it's beautiful out post-storm, another low 70's morning, so perfect for a run! According to my half-marathon training plan, I was supposed to run 30 minutes today. However, I only made it a mile before my left ankle made me decide to stop. I'm sure I could have kept running and managed the pain that I was feeling, but I also thought it would be better to stop since I have my longest "long-run" planned for Sunday. I also figured I've still got 12 weeks until the half-marathon, so I probably shouldn't screw myself over now. So like a good little girl, I came home to ice it and blog about it.

I guess my question becomes, am I experiencing something that I should classify as an injury, or am I only dealing with a slightly annoying pain? I know only a doctor can truly tell me that, but I imagine lots of runners (and other fitness buffs) out there deal with slight pains that they can manage through, instead of stopping everything for something seemingly minor. I mean, it's my own fault that I didn't ice it yesterday, so I guess I paid the price today by having to cut my run short. But in the next breath, I feel like I shouldn't have to be icing after every run to manage my ankle. Or should I?

On another note, beyond the pain that occur in my ankle, does anyone else get shoulder pain? I hold tension in my shoulders no matter what, from being a musician, but I notice on runs, I tend to keep my shoulders tense like I do when I'm playing clarinet! What gives? I consciously try to tell myself to relax, but the more I'm "out there" the more it seems to happen. Sometimes after I run, the part of me that is the most sore later that day are my shoulders, which is just hilarious to me. Is it a me problem or do others experience this too?

Anywho, as always, advice or suggestions are always appreciated, especially in regard to this ankle issue! I just want to wish it away!