Dude..you better go to the doctor..one of my friend had a similar problem..he was doing 100 pounds for his shoulder..he had a pain like yours..but it got really worse after 2-3 days..it started swelling and he went to the doctor and found out that he had build up an infection.

He had a surgery done for his shoulder two months ago ..now he is fine and doctor told him to take rest for 3 months and not to go to the gym for that period...Now he has started doing light weights...I did not mean to scare you but I hope your situation is not like that...

Dont waste your time..get medical help..