how can i relieve rotator cuff pain?

I was building a bed frame with wood. And halfway through hand sanding them down, I started feeling a pain in my smolder. I figured it was just because my body wasn’t used to the movement. But then when I woke up this morning, I can barely move it. It hurts tremendously. I don’t think I tore anything. Im only a 23 female. Any suggestions would be well appreciated. Thank you.