Hi. Greetings. This pigment is quite thick and violaceous in color. Probably you have had a fixed drug eruption. Please see a dermatologist in your city. In Kolkata you could see Dr Ishad Agarwal or Dr Poonam Jalan. You'll need to avoid that tablet for ever in your life and also check why that tablet was given and take a chemically unrelated tablet instead. The condition when active can be treated with short course of medications and creams and later pigmentation will reduce with some creams but may not go away fully. Hope this helps .