I was doing my shoulder/bi/tri day off WBB1 today, and I hurt my shoulder on the 2nd shoulder set. I had already done my military barbell press with no problem, but on the 6th and final rep of my 2nd set of overhead dumbbell press, I was going to fail but as I was trying to drive it up my left shoulder just collapsed and I heard/felt (had headphones on very loud) a bit of a crunching sound, not sure what happened, and I dropped both DB's to the ground. I had a previous injury about 8 weeks ago where I fell out of my couch after waking up and using my left arm stiff to protect my fall, which hurt my shoulder really bad, and I couldn't lift it above my head for a few days. Gradually it went away, and as I got back into lifting 6 weeks ago, I could always feel just a slight pain as I finished a rep doing any shoulder lift, but nothing that was ever detrimental to the lifting. I was able to finish most of my workout without a problem, as the bicep and tricep lifts were no problem, except skull crushers which hurt my shoulder too bad. Also this pain is nothing compared to when I fell out of the couch, but I'm assuming I reaggravated it. What should I do to take care of this, and to ensure it doesn't come back? I can rotate my shoulder around in all directions, just with pain, but it feels like after a week after my previous shoulder injury, so it's not nearly as bad. Thanks for all replies, I am doing really well in the gym and don't need injuries to hinder my progress.