Due to to repeated itching also the color of skin is likely to change into black.
Itching of groin region may be due to
1. Ring worm infection
2. Seborrheic dermatitis.
3. Pubic louse infection
Small lumps may may be furuncles secondary to itching and scratching as bacterial infection.
For fungal infection
sometimes topical Clotrimazole
alone may not be sufficient. Oral systemic treatment with antifungal antibiotics and antihistamines for 4-6 weeks. Consult your dermatologist
and he/she will help you.
Get well soon.