22 year old female, 5'9", 117 lbs. Found a pea sized lump under my left axilla this morning. It is tender to the touch, slighly red, and it hurts to raise my arm. How long should I let this persist before I see a doctor? What could it be indicative of? I have not changed deodorants for about a year now, no injury or trauma to the area, no allergies (seasonal or other), no recent illness.