Blue Norther Duathlon - misnamed

I cannot believe it has been like a week since I have been here. I continue to have a nagging calf muscle in my right leg. I hate injuries - acute or nagging. My calf seems to tighten up about 2.5-3 miles into any run. I recently changed from a neutral shoe to a stability shoe on the advice of a running store and I am wondering if that is the major cause. I have also eliminated just about everything else I can think of except dehydration and nutrition. I am going to really hydrate and also run in my neutral shoes and see it that does the trick. Maybe my stability shoes are too stable???

I am doing the Blue Norther Duathlon on Sunday. It is in the town I grew up in and I think it will be fun. It will also be hot....not much Blue Norther...it was over 90 today and is forecast at 89 tomorrow. Sunday is set up for the mid to upper 80s so not much coolness once the sun comes up. It is run bike run so I hope the calf performs well.

Any other thoughts on the cramp would be appreciated.