The image and your description (ring-like patch with a white layer/scaling in the groin area, present for 20 days, occasional itching) strongly suggest tinea cruris, commonly known as jock itch or groin ringworm—a fungal skin infection caused by dermatophytes thriving in warm, moist areas. 
The white/grayish scaling, darker surrounding skin with hair, and location in the groin folds are classic for this. Less likely but possible differentials include candidiasis (yeast), irritation from sweat/friction, or other conditions like lichen sclerosus (more purely white patches), but the “ringworm kind of patch” points primarily to fungal tinea. It has persisted for 20 days, so self-treatment alone may not be fully resolving it.
Next Steps
1. Start an over-the-counter (OTC) antifungal cream immediately, such as clotrimazole (e.g., Candid in India) or terbinafine (e.g., Lamisil or Terbicip). Apply a thin layer to the affected area and a bit beyond it, twice daily for at least 2–4 weeks, even if symptoms improve earlier—stopping too soon often leads to recurrence.
2. Consult a doctor (preferably a dermatologist) soon, especially since it’s been 20 days and involves a sensitive area with a white layer; they can confirm the diagnosis (possibly with a simple skin scraping test) and rule out other issues or prescribe stronger oral antifungals if needed. In Mumbai, you can search for local dermatologists on Practo, or hospital apps (e.g., Lilavati, Hinduja, or government options like KEM).
3. If no improvement in 7–10 days of proper OTC use, or if it worsens/spreads, seek medical care promptly to avoid complications.
Health Tips
• Keep the area clean and dry: Gently wash with mild soap and water daily (or more if sweaty), pat dry thoroughly—use a hairdryer on cool setting if needed. Avoid sharing towels.
• Wear loose, breathable cotton underwear; change if damp from sweat. Avoid tight clothes, synthetic fabrics, and excessive moisture. Use an antifungal powder (like Candid powder) after drying to absorb sweat.
• Home remedies (supportive only, not primary treatment): Diluted apple cider vinegar or tea tree oil (diluted well to avoid irritation) may help mildly, but don’t rely on them alone—stick to proven antifungals. Continue remedies consistently and avoid scratching to prevent secondary bacterial infection. 
skin conditions in the groin need professional evaluation for accurate diagnosis and to prevent spread or recurrence.
Book an online dermatologist appointment today on Practo for quick relief and proper confirmation—many slots are available same-day in Mumbai!