Aches and Pains

I took the day off yesterday (aside from a medium sized walk with the dog). My left calf is really not well. It feels like I have a tennis ball wedged in the meaty part of my muscle. It gets slightly better as I walk, but I am not sure that I could take the pounding of a 5 mile run, so I may opt to hit the elliptical - or a longer walk with the dog. Rest, right? I am icing it too, and using my STICK. I need to NOT be injured for long - I have exactly ONE MONTH until the MARATHON!! I am getting crazier by the day!