When working muscles with bad PIP, are you more susceptible to injury or infection caused by trauma?

Late last week I made the jump to pinning delts, fri n sat. Got pretty considerable PIP n swelling, but it's virgin muscle so I expected such, especially with painful prop.
Monday I worked chest n killed it. Both of my delts were in a good bit of pain before I started getting warmed up and as my workout progressed my left delt, pinned fri, started to loosen up and the pain completely went away. My right delt on the other hand, pinned sat, tightened up n started to hurt more n more throughout the workout. I worked through considerable pain up until the end when I had to finish early when my shoulder/arm started to go numb.
Now post workout, my left delt is completely pain-free n feels great (working out relieved the soreness), but my right delt is swollen pretty bad n bright red, warmer to the touch. To move my shoulder no longer hurts, but to press on the inflamation hurts like a b*tch.
I don't believe it's from infection, I'm using the same vial I have been for weeks with no prior problems.
Could pushing through the pain have caused more trauma to the site/muscle? Common sense would tell me yes, but I've worked quads/glutes with bad PIP many times with no ill effect. It always seemed to help with the soreness/dispersion in the past.
Anyone else experience this? Not sure if it was just a fluke or it's fairly common. I've pinned countless times in the past n never experienced this.
Maybe I forced the oil out of the muscle?