Hi there- I have a blood clotting disorder, and take coumadin/warfarin to control it. One of the weird "rare" side effects is something called 'purple toes'. That was actually the second thing that I thought of. The first was a clot in the vein that is obstructing blood flow to your feet. When I have a DVT (clot in my leg) I get this really terrible aching at night. I know that hormones can increase your chances of getting a blood clot. Not to completely alarm you, but it's worth getting checked out.
First of all, are you a diabetic. You may not be getting enough circulation to your feet. Also people with diabetes have alot of feet problems. I would check into that. Just a suggestion. If you haven't been diagnosed, then I would check into it. My dad is a severe diabetic and he has to be very careful with his feet. One cut on his toe can lead to major infections.