Round Rash

I woke up with painful round rash located directly under my armpit. It is not hot where I live, so I do not think it could be a heat rash. I did not get much exercise. Ideas?

You can get a fungal infection - sometimes these things break out in particular in response to hormonal influences or as strange as it may seem it could be a moth - especially if you have a cat or dog
Keep area of Nice and clean and wash with warm water and soap - you can also swab with baking soda (baking soda) and warm water to see if it helps. Pat dry and let the deodorant out to give him a chance to reduce - when it is dry on the cream - you can make at least 2 X per day
Try anti fungal cream such as Canesten or if that does not work, consult your doctor - it may just be a thing of allergy your deodorant and you may need other treatments such as cortisone-type cream for help or if it was ringworm You also need a prescription cream for it