LOL...I don't know why the donuts do it for you...but it is ironic that many people find they 'go' easier when eating junk...they don't call 'em 'sliders' for nothin'!!! I suppose it could be your body's attempt to get rid of it...like it does when you get food poisoning...LOL! Seriously, though...it might be the oil in it.
I'm assuming that you had eaten something prior to eating the donut...and that this wasn't your first post-fast food...please tell me that you broke your fast with something besides a donut!!! Eating in and of itself stimulates peristalsis...so it could be as simple as that.
Sorry...I don't know anyone in NW Indiana...go to i-act.org and click on referrals...and also ask for recommendations at health food stores or alternative health practitioners...see if the same name keeps coming up.