i haven't been on here for a while so i thought i'd check in. you sound a lot like me! i have had daily diarrhea/loose stools for 23 months now...almost 2 years! mine started out of nowhere too. it just started one day and never quit! i also didn't understand how that could be. you're fine one day, and the next, you're live changed because of your "bowel habits".
here's what i have done. i have also had ALL of the tests you can think of...colonoscopy, EGD, scans, etc. all show nothing. i also am losing hair really bad.
i have changed my state of mind. i have found that if i try not to think about it and fill my day with things i enjoy, it actually has gotten better. i also feel better! do you have a hobby? i picked up photography and it's my "escape" from the stress and worry of the bowel problem. instead of going 5 times a day and constantly cramping, i, for the most part, only go 1 time a day now and that's about 10 minutes after i wake up in the morning! i can handle that.
so, try destressing your mind and body. do things that are fun for you and that you enjoy and focus your attention on that vs. your IBS.
hope this helps you!shelly