What could be causing pain under my arm?

Answer by  Atomicrayon (2504)

If it's an allergic reaction, like there is swelling or bumps. You may need to try a different brand of deodorant. This is a common side affect of most deodorants. It might be a stress related pain from working out or sporting activities. Lastly it might even be something as simple as the way you're sleeping on it.

Answer by  genuis2010 (123)

Nodal infection or enlargement is the most common cause of pain under arm. other causes include infection,allergy or shoulder muscle strain. In females, pain under arm could be a radiating pain from a problem in breasts.Sometimes metastatic carcinogenic cells may also cause pain under arms.

Answer by  Janna1 (5)

I feel pain under my arm because of the lactic acid produce in my muscles after doing strenous exersices example running in short period of time. Lactic acid forms because my muscles under my arm respire anaerobically. The building up of lactic acid in the muscles results in muscle fatigue and the muscles will be painfull.

Answer by  Platynum (39)

Your probably just sore, ive never had pain under my arm. Try resting it and not moving it for a while. This normally helps all pain.