if his shell is getting softer and softer its prolly a calcium deficiency, even if u are sprinkling all his food with calcium suppliments. there are some foods that have calcium inhibaters in them (oxalates)that if given in large quantities will completly stop calcium absorbtion, http://www.peteducation.com/article.cfm?cls=17&cat=1797&articleid=2434 try looking here, also does ur calcium have d3 in it if not i would recomend it to indore sulcatas