My baby has a dent in his lower back. Above his right butt cheek, to the right of his spine . The docs have never said anything, and at first I thought it was just a dimple and didn t think anything of it. The dent/crease seems more pronounced now and I m starting to get concerned. It s slightly discolored (a little tanner than the rest of his back), so I m wondering if it could be a birthmark . I don t know if I should wait until his 6 month check-up (he s 4.5 months now, was just at the pediatrician 2 weeks ago), or make him an appointment...