Saddle issues

So I think that Lucas needs an ajustment to his saddle. We have a collegiate convertible close contact that up untill this point we've both liked. However now it seems to be causing him problems. It seems to be pinching just behind his withers and its pivoting there and not settling down on the rest of his back. Hes just into the MW on the template so Im going to put that gullet in for the weekend and see if that makes a difference. (Hes' got the Med in now) We'll see.