Swollen, itchy red bumps appeared randomly under both of my arms today in the armpit region. what could this be and how can i treat it? thanks!

Bumps: Both contact dermatitis and folliculitis can cause a rash in the armpit. Sometimes shaving irritates the hair follicles, causing them to inflame, then become partially blocked. Consider using topical antibiotics, like benzoyl peroxide. If you think this is a contact allergy to a chemical like those found in deodorants, consider topical hydrocortisone cream