There can be a variety of reasons for that. Allergic reaction to deodorant or even food. Some people are known to break out under their arms during stress, periods of intense workout or from eating a lot of sugary, salty foods. If the problem persists, you should see your doctor.
The herpes virus causes cold sores.
Te herpes virus causes cold sores.
No it causes itchyness.
I don't know, I've only ever had tingling in the left armpit. Sorry, can't help you.
staph
FYI canaker sores are not related to oral herpes (the virus that causes cold sores). See related link for some remedies.
Impetigo causes weeping sores, its the 'weeping' that is contagious. Be it via skin to skin contact, a towel or virtually anything. When the sores are fully scabbed they are not contagious, its only the liquid inside the sores that is contagious.
on howrse its causes painful sores and scabs
Breast Milk
Yes it does
Could trigger a break out if you suck your thumb rather vigorously, but that isn't what causes cold sores. Cold sores are caused by a virus.
Getting a sun burn doesn't cause a cold sores but it can trigger break outs. The oral herpes virus is what causes cold sores.