About A Year Ago My Left Foot From My Big

about a year ago my left foot from my big toe down my foot turned black with burning inside and out....well it is starting to turn black starting at my left foot big toe, however it is cold now. What could cause this to happen to me? Also, my face (only the right side) last night went numb and very cold. It started with the right top and bottom lip moved up to my right nostril (inside and out) its very cold or it was last night I am not experiencing the face numbness right now, however, I am very concerned about my foot turning darker by the day....Please help. Thank you.