Wow! Did your situation ever bring back bad memories of when I was working and dealing with gut issues.
The only way I could function was to get up at 5:00 a.m. to allow for bathroom time, and eat NOTHING during the work day. I relied totally on hard candies just to have some kind of energy to make it through the day. I did this for a good 5 years, and it was horrible, but I survived it. It amazes me what the human body can tolerate and still keep going.