Hi Thanks for your query From the description of the skin lesions that you have developed, i suspect that you have developed lesions of Fixed drug eruption. Now this is a type of skin reaction to the intake of certain drugs especially nitroimidazoles , pain killers and diuretics although there is a long list of drugs which can cause such a reaction over skin. The lesions are round or oval. Initially the lesions are reddish and with time ,they turn darker and become blackish or brownish in color. Firstly, it is important to find out the cause. So try to see if you have any history of intake of the above drugs or other common causes of FDE. Next you need to apply a topical steroid cream something like clobetasol craem over the affected area atleast twice a day . You can use it for for months together till the time the pigmentation subsides. Hope it helps Dr Geetika Paul