I started walking on a treadmill about 3 weeks ago, and ever since then, my calves feel swollen all the time, sometimes they fee

Could be your shoes, speed, distance, or something in your body such as a muscle imbalance. Try walking slower and for less distance, not more than half the distance you're currently doing. Be sure you stretch before and after your walk. Here are the stretches I do before and after my running. Try walking around your neighborhood instead of on the mill.

I think I figured it out, it's probably muscle, duh...I never thought about the fact that I'm exercising and building muscle in my calves...

I feel a little silly now...Thanks for your response though.  I appreciate the stretching exercises, sometimes my shins feel kindof tight, any idea how to stretch that front muscle?