What Causes Spreading Reddish Itchy Skin And Residual Scar Thereafter?

Hi I got skin infection before 3 months and got treatment for that when i taking medicines it will be cured and when i stopped that means it again started.

The 1st infection will come like redhish in color and then some time i will get the itching feeling on that then it will be cured and came as black marks. Previously i got this in leg side only now it is spreading in the back side and in abdomen also can u please suggest in this,