An easy way to assess on yourself if you should be pressing a weight over your head. Grab a furniture slider and place under your hand. Two hand positions will be used. Take your shoulder through a full ROM from the hip to overhead. Keep constant pressure on the slider. Keep the lower back in contact with the floor. This ensure that the anterior ribs don't flare up. Essentially this keeps you from arching your back, which is a cheat for lack of shoulder ROM. You can see me pause at the 2 o'clock position. That's me lacking a little motor control. With enough repetitions this should iron out. If you can't do this without arching your back or you can't apply pressure that is a sign to no go on over head lifts. This will save your lower back or anterior shoulder pain. Also, at no point should there be pain behind the shoulder. This is closing angles pain and should be addressed by a health professional.