What skin disease is this?

My mother is a diabetic for last 15 yrs She is on insulin for last 4 yrs
For last 1yr[May 2005]some spots on her skin has started to appear first on the thighs and then the legs
0ne spots on the stomach.
The spots come very slowly at infrequent intervals
Overall till n0w there are 7-8 spots in this 1yr+ time

Description of the spots -:
The spots come as small dots. Red dots and then keep on growing big and then turn black. ALL THE WHILE IT REMAINS PLAIN. THERE IS NO ERUPTION TYPE LIKE IN RINGWORM. IT HAS A BLACK SPOT IN THE MIDDLE . The Skin doesn’t bulge at all. It remains soft as silk from the time it is red tillit turns into black.After it has turned black it remain again the same , SHINY BLACK. . All this happens in a week span. At times only there is itching,else the patient has no it ching problem as such. You can say in the span of 7 days say once or twice only the patient may say itching. The itching happens only when the skin is in the RED stage, not in the black stage.

Now she was 1st shown to a skin doctor in September 2005 who identified it as Lichenoids. He gave med for a week and some skin cream. The skin cream only relieved the itching. But it did not stop anything else. The treatment was continued for only 10 days and afterwards I think till now 4-5 spots have come up.

All in the lower part of the leg and moving to the thighs.

Now recently 2 weeks back she was shown to another skin specialist , who has identified it as eczema. She has given some skin cream no internal medicine and in the last 10 days the old black scars have remained the same.
But today a new spot is seen on the upper thigh.

She also has a issue of excess perspiration from april 2002.
Her perspiration doesn’t relieve at all. The allopaths keep on saying it as because of heart problem. In 2002 her heart pumping was down to 23% which has now come back to 65%. Her sugar levels also for last 2 yrs are around 150