I had it in high school. Nathan has been battling achilles problems for the last couple of months. Hell, I think it happens to all of us from time to time. Rest and ice. Stay away from too many climbs when you are running until the pain is gone. Probably stay out of spikes as well...especially if you don't have any races requiring them coming up. If it's just sore, you should do LIGHT stretching after activity as well. VERY LIGHT. Try doing the wall push stretch, but bend the "normally" straight leg a little to get a little bit more of a stretch in the achilles. Another thing I had athletes do was take the Stick over it very slowly, putting pressure while pulling up. Be patient as well. You are in too good of shape to let it ruin you. A couple of days off with therapy should be a big help.