Hello there....with the discription you have provided...it is very possible that you may have subluxation of your right shoulder joint...do you in recent days fell on an outstretched hand or had your shoulder pulled/jerked in a forceful way (like in holding a bar on a moving bus)..the pain should not be a problem but if you say u feel a gap presence it is better you get your self assessed by a therapist or an orhthopadecian and if subluxation is present it needs to be fixed first also taking an X ray in AP/Lat view would help in aiding the diagnosis.