It seems that you are having Schamberg's disease.
It is a form of capillaritis..also known as progressive pigmented purpuric dermatosis
There is a mild inflammation in capillaries underneath skin of feet and legs.
It is asymptomatic and benign condition.
It has no relation with with tuberculosis
or its treatment.
The color in disease is due to micro blood clots
You consult dermatologist
for firm diagnosis.
Tab vitamin A and K may be taken for long time.
Thrombophob oint. application may improve the disease.
I feel you may improve after few months.
I hope you got my answer.
Dr. Ilyas Patel MD