My GI doctor prescribed Nortriptyline for me also, made me sooo tired during the day I stopped taking it. I will try the histamine blocker, I've tried so much else. Also going to try glutamine that people on here have used with success.
My diarrhea improved a lot since I started the low inflammation diet Dr Pimentel recommends. Its far less restrictive than LowFodmap but same principal. As with you, I have done a LOT of reading to figure things out myself as my doctors have so far not been much help and it takes forever to try each thing they want to do and I still have all the IBS symptoms, bloating, cramping, takes hours for elimination to happen ( but I had the same with the diarrhea, took a long time for it to come out, so seems the same problem whatever it is whether soft or harder! ) I've done every test with negative results except motility is slow. I just did a round of Rifaximin and it didn't help, I know often it requires more than one round, but its so expensive! I've had this for 2 years with only a couple months of feeling sort of better, I know a lot of people have more serious issues, but I feel so badly from this its totally impacted my live, along with the IBS I have a raging reflux problem. I mostly have to stay home, feel too bad to do anything other than basics. Glad people are posting with things that have helped them.