Hello Thanks for query . Light brown spot on Venus mound which has recently turned out red is most likely to be a Sebaceous Cyst which is in a stage of induration and impending infection . The skin in genital area is rich in sebaceous glands and hence prone to get more sebaceous cyst due to accumulation of sebum beneath the skin. Normally they fade away without treatment however they need to be treated if increase in size or get infected. Take antibiotic like Doxicycline with Diclofenac twice daily for a week . If persists even after taking antibiotic you may need to consult qualified General Surgeon for assessment .You may need to get it removed (Excised ) in Totto under local anesthesia . Dr.Patil.