I Am Diabetic With Neuropathy. No Feeling In Feet Or

I am diabetic with neuropathy. No feeling in feet or hands. A week ago today I spent the day with a plastic ball in the toe end of my left shoe , no feeling so I didn't know. I did not see the issue until the next morning getting into the shower.
There were about 6 smaller pressure ulcers on my toes - the big toe and two toes next to it - all open and bleeding. Looked bad as you might expect. Went to emergency room and was treated. The emergency doctor referred me to wound care but they will not see me until this coming Monday.
I was given two different antibiotics and a antibiotic cream which I apply 3 times a day.
Today I am seeing a black spot about as big around as a pencil eraser in the biggest ulcer which is at the end of my big toe on the under side.
I have lost all the toes on my right foot after a like situation when they turned black due to gangrene. This is different very black and in the center of the ulcer. Any clue ?