I did the same thing last summer. I didn't feel the heat until I was half way to the water, then I had to decide, do I go to the water or back to the car. At that point, I thought the sand was hot, weird thing was, no one else was complaining. I headed for the water, once hitting the wet sand, my feet felt better, but the same as your feet, like something was stuck on them. Same as you, blisters on every toe, that's when I felt even worse!!! I had no idea how I would get back to the car.My toes hurt for days after. Since that day, I wear swimmers shoes until I get to the wet sand.