Always good to get checked. Good to get some x-rays, and be able to at least eliminate any bony issues. Also, and most likely, is probably the classic combination of too much, too soon, and a lack of baseball specific stretching and strengthening. Baseball is a game of rotation and needs to be stretched and strengthened that way (as opposed to football, which is a straight line/planar game, and needs to be trained that way). I see the following combo of issues all the time (I too have a 13 y/o who has played high level travel ball for four years, and have seen elbow pain every year with team player, and again with a player just last night. Not my son.). The elbow gets beat up due to loss of mobility and ROM at the shoulder joint (most importantly shoulder internal rotation deficit), posterior shoulder soft tissue and capsular tightness, some scapular control/strength issues, questionable posture (preach for player to hold proud chest position), biceps tightness, and to a lesser extent and less often, wrist joint stiffness and restrictions. The elbow tries to make up for the lack of motion above (shoulder) and below the elbow (wrist), and can also be influenced by poor posture. Elbow will become over-stressed and that leads to problems. Probably no permanent damage yet, but need to find and fix the "causes" (see above) for the symptom (elbow) to settle down and stay healthy. After seeing the ortho doc, finding a good sports physical therapist can be very helpful.
