shoulder pain!

[Softmuscled]

2 days ago at the gym i tried to prove to someone that i can bench press a certain weight.. which is pretty close to my max. I pressed it 2 times but i forgot to warm up. Right now everytime i try to bench press my shoulder really hurts. It only hurts when doing flat bench press as it doesnt hurt on incline or shoulder presses. I think i prolly pulled or strained it. I am currently doing a powerlifting routine which is suppost to increase bench press and squat strength. But with this shoulder injury it might slow me down. I dont think this is a rotator cuff injury as the muscle hurts not the joint. My question is: what should i do for the shoulder to heal? just rest? go lighter? or ice it? what? I only hurts when doing bench press and the pain is more inside of the shoulder musle then outside. Thanks