Problem with my model of T-rex

Well I`m with a problem in the model. The polygons in the nose are stretching, mode sculpture with many levels of multiresolution.

How solve? Thx.

Link for download:

You have some extra vertices in your model, you can see them by going into Edit Mode, and with everything deselected press shift + ctrl + alt+ m, this selects non manifold, or where your mesh is open. You can select all and press w and then remove doubles to rid those, but it still was getting that stretching effect. However that was fixed by deleting the four faces between the nostrils in the center and rebuilding them.