Hi Evening

There's every chance you're going to get far better answers than this..........just that no-one has answered yet so:
Do you think maybe it could be an allergy to something?? Maybe a different laundry product, if any has remained on your clothing...........even if it isn't anywhere else there could be more contact in that area?? Maybe a different toiletrie product you've tried.........
Maybe a heat rash?? If it's hotter and there's more friction in that area??
Maybe eczema??
There could be a chance that you're more susceptible to something like the above if your immune system is lowered with fighting off the other recent issues...........

But if you can't get to the doctor yet, then I'd suggest checking in with a pharmacist for some advice and treatment..........even if it is going to be a temporary measure until you see your doctor............

So, just some thoughts.............and hoping you get some better answers

Alison