When sitting down no matter how i sit i get rushes of heat to my left foot only. it doesn't hurt. it's just strange. been happening for a week. why?

See below: If sitting initiates a surge of heat to only your left foot then a condition known as radiculopathy could me starting in your lower back or you could be having engorgement of the veins around the nerve on the inside of the ankle causing a thermogenic form of tarsal tunnel.

Neuropathy: A nerve is being compressed or impinged on. Which one would be determined by clinical exam which may need diagnostic testing.