For the last 8 months I have been having mild itching sensation that comes and go under my armpits. I haven't given it much thought and just kept on.
On Monday I suddenly had a breakout in both armpits in which small flattened pimples came out. The rash is quickly advancing and is now covering the whole axillary region of both my armpits and all the pimple have joined to create a unified reddened thick surface .
The rash is very itch and a week's treatment of topical hydrocortison and antihistamines have not helped at all.
What other differential diagnosis would you offer?
Can it be Scabies?

Mind you I am swimming almost every day but have been doing so for a very long time (even before the original itch has began).

Thanks