Top of left foot nickel size bruise grey under that is red. only hurts to walk put too much pressure on it. toes. 3 4 5 hurt to move. no stairs?

Ice it: You can use stairs....Just alter the way you walk. Use more of a steppage gait. Lifting the foot shouldn't hurt as much as dorsiflexing it.

Stairs are: Really hard because you flex the ball of your foot and usually bend your toes. You might have a small fracture under the bruise with that much pain and might benefit from a surgical shoe. I might not cray it right away but watch it and see how you did in that hard soled shoe. Ice it 15 minutes 3 times a day for a few days. ( you did not say what you did or when but it sounds pretty new )