I'm am having problems finding the right bit for my 13 yr old appy gelding. He has thick lips and there pretty short for his size and him canine teeth are high so it's hard to put the bit at the corner of his mouth without the bit clanking him canines. Every bit i've tryed on him, when i pull on the reins it makes the corners of his mouth bunch really bad almost like the bit is squishing the corners of him mouth and he open his mouth. I have tryed the follloing bits on him and none of them fit him: Low port curb, high port curb, swivel shank curb, non swivel shank curb, full cheek snaffle, D ring snaffle. Some were 5'' and some were 5 1/2'' mouth. How can i find a bit that doesn't make the corners of him mouth mouth bunch up?