On Wednesday Morning I Woke Up With A Slight Pain

On Wednesday morning I woke up with a slight pain in my left shoulder, where the shoulder and upper arm meet. Today(Thursday) the pain has intensified so that I cannot use my left arm. This is not a shooting pain, but localized from where the shoulder meets the upper arm. I have taken 2 ibuprofen capsules and tonight Tylenol PM. It hurts when I press on the upper arm, but most of the pain is caused when I try to lift my arm. Any thoughts? I am 60 years old and have recently been treated for gout with prednisone. I have been done with the prednisone for about a week now.