It is not uncommon for some fungal infections to resist terbinafine, the active ingredient in your current treatment (Terbikem 250 mg and Tebina 1% cream). Please do not worry, as this is manageable. Since you have seen no improvement after 21 days, you should consult your doctor to confirm the diagnosis. They may switch you to alternative generic antifungals, such as oral itraconazole or fluconazole, along with a different topical cream like luliconazole or clotrimazole. Meanwhile, keep the area clean and dry, wear loose cotton clothing, and avoid sharing personal items. Do not start new oral medications without a doctor's supervision.

Since antifungal creams like Candid (clotrimazole) and Tebina (terbinafine) haven't helped, your rash is likely not fungal. It could be an inflammatory skin condition, eczema, or a bacterial infection like erythrasma, which often leaves dark spots. Please stop using the antifungal treatments to avoid further skin irritation. For temporary relief from itching, you can apply a mild hydrocortisone cream or a plain moisturiser. However, because this has persisted for six months, I highly recommend consulting a dermatologist. They can properly diagnose the issue and prescribe targeted treatments, such as prescription-strength anti-inflammatory creams or antibacterial medications, to safely clear the rash and fade the dark spots.