I Have Noticed My Right Shoulder Area Has Been Stiff,

I have noticed my right shoulder area has been stiff, when I move it, it feels like my muscles are tearing. Putting any pressure on it sends raidiating pain down my arm. I cant sleep on it. Some movements I can hear a popping sound. I have been to the hospital e.r. and they said they could not find anything wrong besides to tell me to put heat on it and if it still hurts to follow up with my doctor because i would need a mri done on my arm and refer to me to a orthopedic doctor.