Hi Kmb-
I can relate to your post. I am about to turn 54 and am 50 pounds overweight. I am completing my third week feeling good about that but also feeling somewhat discouraged that the area below both knees has started hurting only while running. Could be several things like shoes, gait, weight. I'm telling myself I've been on the couch for way too long so the pain will subside (hopefully) when I get stronger and the pounds fall off.
Best of luck to you.