I had the colonoscopy done a couple of years ago, and it wasn't too bad. They drug you pretty heavily for the procedure so you doze through it. The pre-op "clean out" is the worst part.
Don't know anything about Equalactin. I take peppermint oil caps or Valerian for bowel cramps/pain. I know I feel better if I take a daily fiber supplement, but I'm not very consistent...it just tastes SO nasty.
While the tests won't *prove* you have IBS, they are important to rule out other diseases. You should consider some kind of bowel imaging test to rule out cancer or inflamatory conditions.