RE: Shoulder Is In Pain :(
I done exactly the same thing last night. I usually use dumbells and decided to do barbell with a mate. he put 110kgs on the bar coz he reckoned that if he could do 5 reps with it then I could. He was spotting for me but it was more like him deadlifting the weight off my chest. So today I woke up with a sore shoulder and I'm gonna take a couple of days off to recover.
Anyways, if you got muscle soreness I always find that Ibuprofen Gel does the trick. Get some from tescos and really rub it into the sore area every few hours. It will hurt whilst doing it and will ache the next day but what it is doing is breaking down any swelling and trust me the day after next you should be feeling a lot better. Hope that helps