I never found gastroenterologists any good. If he is no good then find a colo-rectal surgeon instead - they have more expertise in the whole gastrointestinal field and functional problems like the pelvic floor disorder and muscle control etc - a good colorectal surgeon will give you every test under the sun to do with your large bowel and rectal function - some will also test the small bowel. It all very much depends on your history and symptoms.
I am from UK so things are probabily slower here as they dont like spending money on you.
so good luck in your quest for health.
Karen 48 years old
1997: Diagnosed IBS
2003: Pelvic Floor repair
2006: STARR surgery for mucosal prolapse/Obstruction/diagnosed slow transit constipation
2007: Sigmoid resection-partial volvulus resulting in worsening of colonic inertia (cleared obstruction though)
March 2009: Loop Ileostomy
23 Sept 2010: Ileostomy reversal