That's quite an unusual problem! Most of the time you'd see tearing in the muscle, and the deltoid is easy to see because it's so superficial. You may have burst a few small blood vessels which have bled into the iinterstitial spaces or fascial layers. My advice to you is to see a physio asap and get them to have a good look at it. You would benefit from treatment to clear that old blood out and get some movement back in the shoulder.
I've seen something similar to this when someone purposesly put little holes in their muscle, which caused a bleed. 
Must have been a killer workout! What exercises were you doing?
Doc.
Winners make it happen...losers let it happen.
Qui audet adipiscitur.