The recurring dark marks are likely a fungal infection. Creams like the one you used often contain steroids, which temporarily suppress inflammation but actually allow the fungus to grow deeper, causing it to return when you stop. To cure this permanently, you should stop using that cream. You need a dedicated, steroid-free antifungal ointment (such as clotrimazole, luliconazole, or terbinafine) and potentially oral antifungal tablets prescribed by a doctor. Please consult a dermatologist for a proper diagnosis and prescription. Meanwhile, keep the area clean and dry, wear loose cotton clothing, and avoid scratching to prevent further spread.

For a severe, persistent fungal infection, over-the-counter options are often insufficient. You likely need stronger prescription treatments. Effective topical options include generic creams like terbinafine, luliconazole, or ketoconazole. For stubborn infections, a doctor may prescribe oral antifungal tablets such as fluconazole or itraconazole. Please consult a healthcare professional before starting oral medications, as they require a proper prescription to ensure safety. Meanwhile, keep the area clean and dry, wear loose cotton clothing, and avoid sharing towels. This condition is very common and highly treatable, so please do not worry a quick doctor's visit will help get you the right, effective treatment.