severe left arm pain

My son slept on my left arm every night for about 3-4 months, around the bicep area.  I started have severe pain all the way down my arm and in my shoulder.  I was wondering if it's possible that the pressure damaged something in my arm or pinched something.  I've had an MRI of the cervical neck and all it showed was arthritis at C5 and C6 but no pinched nerves or bulging disc.  I don't really get pain until I start using it.  I have no pain at night but pretty consistently all day.