I've never heard of an "aura" happening in your legs. I think you get them before migraines. It's something neurological. Any neurologists out there?
Do you have varicose veins? I had very achy legs from varicose veins while pregnant. Lately they flare up before my period. But recently, my legs ached a lot when I had a UTI. Not sure if it's the same thing you're experiencing, but I'd love to hear if anyone else has these issues too.