I have that exact same problem. I feel like my feet weigh a ton and its a struggle to move a few steps. I'll be interested to see if anyone knows the resone for why this is.
I have that problem sometimes too, but it's like, my Mom or someone I love will be in trouble, or even myself, and I can't move to help them, or myself. I think it just feels like that, because we get so worked up in the dream, that our bodies in real life are trying to move. Since we're dreaming, we can't move right, so it just feels like slow motion in the dream. :0 Just my best guess, not idea. Xp