I suffer from the same symptoms as you, but so far am only taking Azilect. I've had a colonoscopy, twice, tested for Celiac, lactose and lost week glucose intolerance. All have come back clear. I think the next step is testing the level of bile not reabsorbed into the body.
The constant running to the loo is a nightmare - I have to stop on journeys to use toilets in shops as I know I won't make the next 5 mins home, going out on a walk and half a mile away know I have to get home there and then, or I will be in trouble.
Been going on so long now - there has to be an end in sight.