Anyone super medication sensitive

I have suffered from IBS (mostly D) for over 30 years. I am super sensitive to meds, fiber and food. It has gotten so bad I am having trouble leaving the house. I find that the least bit of a medication to help with the D throws me into C. An example would be I have a 2 hour car ride to pick DD up from college this week. I can usually make it if I take a levbid or levsin SL if I need fast action and one immodium plus only drink water and eat pretzels or a peanut butter sandwich (these are safe foods for me). But the kicker is then the next day I am so constipated that I am in much pain. Taking just one pill or the other does not do enough to help keep the D at bay and allow me to do the drive. I cannot even do more than one dose of fiber (a must with my diverticulosis) a day or I spend it all in the bathroom. I finally have the kind and time down so I am not up at night or chained to the house during the day. I can lay in bed and watch my muscles spasm like seeing a baby kick. My anxiety has intensified in the last year since I have also lost some muscle control over the years from a severe rectal tear during childbirth and a large fistula surgery last year. So urgency has to be taken care of immediately. The only med that has ever helped with the diarrhea was Zoloft when I took it for my fibro pain. I do not want to go back on it as I cannot take anymore weight gain (hypothyroid added 30+ pounds that have not budged in 5 years) and the fact that even on a small dose I felt I wasn't feeling anymore. I have taken more suppliments than I can remember, having allergic reactions to most. I also do self relaxation and breathing exercises which help some but not as much as I would like. I am so limited in what I can eat that I could easily give up food as it is definitely not fun to eat. We have treated my excessive mast cells with vistaril for my IC and allergies but I am currently off it as it too slows down my digestion so much I am miserable. So I usually take it for about 3 months (75 mg/day) when I have a major IC flare which is about every 2-3 years. I currently take Levothroid, atenolol & Aciphex (no increase in D with this but did on Prevacid)daily plus 5 mg valium 2 days a month for severe bladder spasm that coincide with my period. Any words of wisdom? My GI doc I think is frustrated with me as I don't fit the mold. I just had a colonoscopy 5 months ago and except for a small amount diverticulosis my colon does not look bad. They also did an abdominal CT scan that showed nothing (that was another fun experience as no one told me that I would be so sick from the contrast. I literally walked 200" from the test and spent 1 1/2 hours in the hospital public bathroom with sweats and diarrhea. Later they told me that normally your body tries to rid itself of the contrast after you get home. Well not me) If you read all this THANKS for sticking with me.