My shoulder ached for two weeks following an event I competed in. It felt like a muscle ache, but deeper down in the joint. I finally decided to make an appointment with my sports medicine doctor, but getting into the MRI and waiting for the follow-up took another four weeks. In that time, the ache would come right back as soon as I did anything with resistance. I was afraid it was a SLAP tear because I got all Web MD on myself, but it turned out to be bursitis. A cortisone shot took care of it.
So, all that to say, see a sports medicine doc sooner than later just to rule things out if it doesn't go away after another couple days. Lorde Holmes has a famous saying in the Common Law that, "even a dog knows the difference between being stumbled on and being kicked." If it feels like something more than ordinary soreness, embrace the co-pay.