Blisters from Walking/Running?!?

Bobanji

OK, So I've started working out for a couple of weeks now. Mainly doing weights and elliptical. I decided I want to start using the treadmill too and within 20 min walking, I had terrible rubbing in my shoe heel. I did 45 min and that was it. I couldn't take it anymore. Take off my shoes and I have a small blister on the back of my heel and my heel feels so tender. Happens every single time I use a treadmill. I have brand new shoes that havn't been giving me a problem so why when I use the treadmill now its a problem? This is always a problem for me, which is the main reason I don't use the treadmill. What can I do about my shoe rubbing? I've tried all different kinds of socks, had my feet measured, new shoes, old shoes. Give up on the treadmill? Once that tenderness is there, I give up my workouts on the treadmill because it is just too bothersome. Anyone else with similar problem? Or anyone know of a better method to deal with it?