How do I get myself to warm up?

I was just outside for two hours and I am super cold. I was wearing a hoodie with no hat or gloves because I don’t have any. My legs and hands were so red and numb I couldn’t feel them. I got inside and as soon as I did, I jumped in the shower. I put the water as hot as I could, and my legs got super itchy and when I started itching them, it left these long red streaks that really hurt to touch.
I was in the water for maybe 15 minutes and I am still shivering uncontrollably. My legs really hurt the touch them, and the streaks are still visible. They are long and red with small dark red and purple dots.
I have a thick comforter on my legs and a blanket on my head on arms and I am still shivering a lot. I also feel like I am getting a migraine. How should I warm myself up?