If it doesn't clear up then get it checked out - it could be a fungal infection. There is a name for it but prob not suitable as there may me sensitive ears listening
It will be fungus probably Tinea, this is the one that causes atheletes foot, but also affects other parts.
Tight BG control will prevent it, fungus love the sugar in your sweat. The doctor might prescribe something like Daktarin or similar, it is very effective.
Sometimes a fungal infection can set off an allergic reaction as well but that really is a situation where a doctor needs to be involved.