Thanks for writing to us.
The constant ache and heaviness in your arm is likely to be due to a nerve injury
due to an electric shock
. The muscle stiffness
due to prolonged abnormal posture can also cause the pain. You need to give adequate rest to your arm as most of the times such mild symptoms do recover spontaneously in 3-4 days.
I hope this information has been both informative and helpful for you.
Dr. Praveen Tayal