Shoulder surgery pain

Two years ago, I had severe pain in my right shoulder and underwent surgery at the hospital. I recovered fully and can perform normal activities, but if I keep my right arm bent for more than five minutes, it becomes very numb. When I sleep, if my right arm stays on my stomach for a long time, I lose sensation in my arm, and then it gradually and severely pins and needles. Recently, I seem to experience this frequently. Is this a postoperative complication? Is it due to poor blood circulation? I am worried whether it is serious enough to visit the hospital. It’s okay when I keep my arm down, but it gets numb when I bend it.