Need running advice and help

I'm not a runner. I wish I was and I am working to correct this. A friend and I have started Couch to 5K and will be running a 5K in November. We are in week 1 still and have done the first 2 days. I went and got professionally fitted for new running shoes and had the digital gait analysis done and the whole deal. My shoes are asics and have a gel insole and it feels like I am walking on a cloud. I'm not a heel striker and was told I have a very good stride. Now, for the first couple of running sessions, I do ok. I come out of the run winded, huffing and puffing and all that. I know I need breathing techniques, but that's a whole different issue. My main issue is my feet. I have mild/moderate pronation of both feet and no arches. I have achilles tendonitis in my left foot. When I run, both of my feet start cramping horribly. It feels like my feet are curling up on themselves. Now, when I do other workouts, like Zumba or the elliptical, this happens too, but it's not as severe, it doesn't last long and I can work through it. It's almost as if my feet are rebelling against shoes. I'm a free-footer, so to speak. I love to wear sandals and flipflops 95% of the time.

So my question is this: Does this go away or is there something wrong? Since I am running for short bursts of time right now until I can build up an endurance level, it's preventing me from physically being able to run the entire minute. Yesterday, I had to walk the last running minute because I physically couldn't run. When I walk during the C25K, the cramping is either very mild or non-existent, and when it is there, it's more a residual from the severe cramping from the running. Are there any stretches or warm-ups that I can do that will help me? I've been to the doctor and without a bunch of expensive labs and x-rays and yadda-yadda that I can't afford, there's really nothing he can do but give me drugs and suggest i find other ways to work out (neither is going to happen any time soon).