From reading some things on energy healing, and studying Reiki, it sounds like you may have some kind of energy blockage in your legs, which is why you feel that warm sensation. I'm not sure, and don't want to diagnose anything,
but if I were you, it wouldn't hurt to excersize your legs more and elevate them.
If it is toxin related, I swear by those foot detox pads that you wear overnight for 8 hours. They pull toxins from the feet glands.
My mother had a boil on the top of her foot that actually went away the next day after wearing these detox pads.
Walking is even good, and to get the lymphatic fluid moving daily, you may want to dry brush your entire legs and feet with a natural bristle brush (dry of course) This will help even with circulation as well as lymphatic flow, when you dry brush your entire body every morning before putting on your clothes.
Also-- I checked on my reflexology chart, and noticed that these following organs are affiliated with the inner side of the right and left foot:
1- Bladder (the inner part of the foot in between the heel and big toe)
2- stomach (the inner part of the foot closer to the toes)
3- Kidney (right in the center of the sole of the foot)
4- Descending colon (one part of that area is towards the inner left foot, just above the bladder spot, but below the kidney area.
5- Pancreas (Right below the stomach area of the foot and above the kidney area)