What do you think is the cause of this weird feeling?

Now I have been having a stiff right shoulder for a couple of days. I can move it just fine, there's no problem with moving or reaching for things. What I do have is in the Scapula area I feel it more so than the left. The coracoid process (bone that juts out around the shoulder blade) feels more prominent on the right hand side. Other than that it tends to stiffen up a lot. Now the reason I think this happened is probably a form of not moving it for a period of time. Honestly being a university student I spend a lot of time on the laptop, I often lean on my desk in front of it one way of the other. Or I rest on my right arm when using the mouse and spend about 70% if not more a day on the laptop either working, facebooking etc. I think this awkward position I put my arm in and leaving it like that without moving or stretching after some time has affected my shoulder. I should say though I do table tennis and handball every week twice a week so that could have an impact. Could you give me some advice on what you reckon it might be and what I should consider doing about it. Thanks.