Shoulder problems....

So lately my right shoulder has been giving me some minor problems. Three weeks ago or so we were playing Walleyball in the racquet ball court and I did something to hurt my shoulder. It was a bit sore for a couple of days then seemed fine. Then when doing the chest press and shoulder press, the outside of the shoulder hurt. It was fine doing the lat pull down, tricep press, rowing, etc. The past few nights when sleeping I'd wake up in the middle of the night with a sore shoulder. If I slept with my right arm up above my head, it would tend to hurt. It doesn't hurt during the day at all except for when doing the shoulder or chest presses at the gym. I mean it's not that bad when lifting. We're talking on a scale of 1-10 w/ 10 being the worst, it's only at a 3 or so. But it's enough to make me notice. I'm only going to lessen the weight if it gets noticeably worse.