I occasionally get a sharp stabbing pain in my armpits, what could cause this?

New to me. Unlikely heart, lungs, or blood vessels! some musculoskeletal strain with workout lifting, stretching etc!?
Doctor can evaluate. Brief, sharp pains that occur in the armpits can be mysterious. If they are in the ribcage, they may be sensations of irritation of the pleura (the lining of the inside of the chest cage). If they are truly in the armpit, then a doctor can examine the muscles, tendons, bones, skin glands, hair follicles, lymph nodes, blood vessels, etc..., in that area to see if there is an abnormality.