Have you tried sitting and lying down poses? You could stand for one pose, then get off your feet for several poses, then try one on your feet again. Pain is your body's way of telling you to be kind to yourself.
I would also consult a physical therapist for reommendations about a therapy program to strengthen the areas that are giving you concern.
Thirdly, IPATIENCE. It took a lifetime to create the body you currently have, it's going to take some time to build it into the body you would like it to be...