thanks for using health care magic
From the description, it is more likely to be a fungal infection
and particularly that of Candida. Candida infection affects
particularly areas of skin fold
with moisture and relatively
poor hygiene. However, Candida or other fungal infections
are sensitive to most antifungal drugs/creams including
, terbinafide etc
Also it could be possible its a chronic reaction to sweat is not
uncommon particularly with people who do sweat a lot.
It will be necessary to see a doctor for an evaluation or try
-use of anti perspirants in the armpits
-anti fungal drugs/creams; miconazole cream twice daily.
If there is no improvement then see a doctor.
Best regards and hope this helps you.