I hear you, Pud's and I am right there with you. My calve muscles do the same thing. I thought, at first, it was age catching up. but in further consideration, I realize it's muscle loss.
I can still flex too, but I have lost some muscle power there. Too much time in my scooter, I guess.
I have been trying to consentrate on doing more leg stretches and exercise and I've noticed that it seems to be helping.
I'm wondering if the hanging is caused by the MS muscles being over-flexed for a long time, while spastic and then, now relaxed.....Like when you're pregnant and then after, your tummy hangs for awhile, until you can get back in shape.
Try not to let it get you too down in the dumps. Cheer up and take charge. I'm with you all the way..