What Causes Vertical Indentation To The Right Of Sternum?

My name is Dinesh Golechha. My 15 years old son developed vertical groove like depression just right side of sternum (around 15 mm deep maximum). On doing relevant testings...his vit-D3 level found exceptional low ( 3), whereas PTH was in normal range. Given 2 shots of Vit-D3 (injectable; 600000 IU) and now on oral supplementation. Last Vit-D3 level is 40, but no improvement in chest deformity...please guide...