I suffer from a similar problem when PG (Not yet but I know it's coming!) and I try to rest with my legs elevated. While you have them up point and flex your feet up and down, this causes your calf muscles to squeeze and assists with circulation back up your legs (incidently this is the exercise they get you to do in the plane to prevent thrombosis as it really gets the circulation going).

Good luck, I know how uncomfortable this can be.