having had rotator cuff repair on BOTH shoulders over the years I can tell you that there is a difference between DOMS and a tendon tear. Things like decreased strength in lateral and front raises are present, constant pain in the front of your delt where your pec ties into your shoulder, numbness at night when sleeping, difficulty in reaching behind you (i.e. putting on a belt) are all good indicators.
If it persists, go see an ortho/sports med doc. They have some simple movements to check you out then may send you for an MRI. Depending on your age, it could also be bone spurs.