Sorry to hear you have it so bad. I only get it on average once a month sometimes up to 3 or 4. I also have the D. I am an airline pilot and yes i feel your pain on the D and no bathroom for extended periods. I used to fly the 19 seat no bathroom commuter planes for 1 to 1 1/2 hour legs yuck. A couple of times had an interesting hefty bag story in the cargo hold. Not fun. Yes this could easily effect my career. I have pu in so much time, money, education, and effort to get where i am an i can't imagine starting over. Hopefully i can get it under control. As for the imodium i can't say i used it only in extreme conditions but i don't have it as bad as you do. the diet(only four weeks in)seems to be working, listen to mags on the exercise. i have a friend in our boat and she does about 50 sit ups per day. this helps in relaxing the muscles. not bad for the abs either.
Hopefully you can get things under control. I won't know for another few months how things are really going. I also take the calcium but to a day about 1200mg, two packets of citrucel per day, lots of water although not what i should take, and i stick pretty much to the diet. no dairy, meat etc.
Good luck and hope you find your solution.