Was running in the yard with the kids after work Friday and the dog got under my feet. Went down hard on my left shoulder with my arm fully extended, kinda landed on the lateral side of my armpit I guess I'd say. Heard it make a noise and initially mild pain. No swelling, redness, outward signs of injury at all. Still no bruising visible.
Yesterday it was a little painful to lift my arm up but not bad (joint pain I mean). Today it's a little better, even. BUT...
We have a door that sticks and I was pulling hard to open it and pulling produced a slowly-building pain that turned very intense. Felt like an immense muscle cramp––enough that I just had to sit still for sevral seconds. It very slowly subsided over several minutes. Now feels normal again.
Partially-torn muscle is my guess? I've never had one before.