Brief Answer:
I suggest a possibility of Fungal Infection/Tinea

Detailed Answer:
Hello. Thank you for writing to us at healthcaremagic

I have gone through your query and I have also seen the Images.

I will keep a possibility of Tinea/Fungal Infection.
Fungal infections are quite common in body folds like axilla, groin, submammary areas etc.
This is because the anatomy is such that body folds are conducive for fungal growth, specially in hot and humid weather conditions.
I suggest you to use a topical antifungal e.g clotrimazole 1% cream twice daily for 4-6 weeks.
An Oral antifungal e.g fluconazole may also be added. Oral antifungals are faster acting and control the condition much better as compared to topical antifungals alone.
An OTC oral antihistamine e.g cetrizine 10 mg once daily will provide you symptomatic relief from itching.

Regards

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