painful muscle

This is for some simple reasons, do u lifted any heavy weight before the pain, or do u use to drink water oftenly, or what type of food u take daily, drink water regularly it must be within 5-8 liters, and take food time to time. Donot lift heavy weights from one side, and don't sleep by one side please u must observe while sleeping u are putting your whole body weight from one side this may some times affects your arms.

my husband had a similar pain in his upper left arm. he had thought it was heart-related but turned out to be muscular than anything. it was caused by some lifting or activity that he was not doing regularly. this could be what you have, but then again, i think you should have a doctor check it further as it may be a condition that needs medication or immediate attention. does a pain killer, like tylenol help with easing the pain?

While this could be any number of things. I have had something similar happen in the past. Mine was more serious with a torn rotator cuff in the shoulder. You should consider seeing a specialist if this does not get better.

Have you tried streching right before bed? You may also want to increase your potassium and water intake. That often solve muscles problems.

Do you know of any injury to your arm? what sports do you play? are you left handed? How long has your arm been painful? can you remember what you were doing when you first felt the pain?