Bully sticks are just baked rawhide. Antlers are tougher and the mniscule amounts of antler that can be chewed up in a day shouldn't rile up a sensitve tummy.
Have you tried "moo tubes"? They're bovine trachea and more digestible than skin, whether in rawhide or bully stick form.
As with any dog toy, check ountry of origin and avoid non-domestc produced.
