Causes of armpit pain?randomly my right armpit started hurting,only with movement,if i raise my arm for example,feels sore but i didn't do anything

Multiple, including:: a Shoulder; A Neck or Upper T. Spine, skin or deeper tissues causes: from any nerve, bone, lung, lining of chest cavity. Some skin causes would include an Infection of sweat glands, or around the hair there. If its occurring randomly, take some Aleve or Tylenol (acetaminophen) for a week or so. If it persists or is getting worse, see your PCP. Good Luck.