I sprained both ankles last week, and now my legs ache terribly, but mostly when I sit or lie down. When I stand up. Or walk, they feel better! What's up with that?

I have had 2 broken ankles, so to sprain them isn't so bad. There are levels of sprain.

Read this website good aid for just that issue copy and paste into your browser:
http://www.kapiolani.org/docs/orthop...e%20Sprain.pdf