Swelling and Discoloration

Mari Ann
Okay, so my feet and legs are already doing the swollen/cankles thing, which I expect as it's 83 degrees....BUT, as you can see in the picture, when this happens, my feet and toes are different colors. I was really distracted at my appointment today, so I forgot to ask about it (and 47 other things)..It happens anytime there is even a little bit of swelling, and everything is normal colored otherwise. Thanks for any advice in advance!!! 
PS: No it's not dirt, I promise.