Sounds like some sort of Colitis (i.e. Ulcerative Colitis). I would recommend a referral to a GI Specialist for follow up.
You can also post in the Gastroenterology Forum.
Your 50 anyway, and should have a colonoscopy at that age, so schedule an appointment with a GI, and get a colonoscopy done. This will A. Find the source of your problem, and B. will knock out your colonoscopy for 10 years.
You could very well have hemorrhoids or had an anal fissure,etc, along with IBS, but again, since your 50, might as well get it done.
go to the doctours and get a blood test. Loose stool should not cause hemorrhoids. It could be a precancerous polyp