I Had A Deep Cut In My Lower Leg, Around

i had a deep cut in my lower leg, around my upper calf. it was a pretty deep gash, so i had to get about 12 stitches. its been healing great up until this morning, where i noticed under the stitches on my calf it has began to sink in, like my calf muscle went into atrophy. is this normal? when i got the cut, it cut blood vessels, you could see them, so maybe a leg ulcer? what should i do? it doesnt hurt, i actually am numb and cant feel my touch on the upper part that is sunken in.