For the past week I've been having an odd sensation in my legs, primarily the left one. Just below the knee almost to the inner side . It's feels incredibly hot inside but the skin outside is normal temperature to the touch. It feels like I am sitting very close to some heat source. I don't have any spots, marks or lesions on my legs. It seems to come in "waves" I;E sometimes it gets even hotter inside although I'm always aware of it feeling hot. Any ideas??!!