This sounds like quite an annoying rash. Unfortunately, no rash can be diagnosed without first being evaluated by a physician. In your case, it is probably okay for you to first see you primary care physician
(family doctor or internal medicine doctor
) before jumping to see a specialist.
The first question I would have for you is "have you changed deodorant brands lately" Changing the brand of deodorant you are using can expose you to a new chemical that you are sensitive to. If you are putting something on the skin of your armpits that you are allergic to, the rash will look very much like poison ivy. Other possibilities include atopic dermatitis (also known as eczema). This is an itchy, sometimes bumpy, red rash that can develop in those areas. Another possibility is that you have s skin fungal infection, which is common in areas of the body where there is moisture and skin comes into contact with itself.
I suggest that you schedule an appointment with your primary care physician. He or she can take a more detailed history of your rash and perform a thorough physical exam of it. If the diagnosis or treatment is at all in question, then you may warrant referral to a dermatologist
. Good luck.