Guategirl,
The remedy for tenesmus is: Mercurious Corr, and it's worked great for me over the years. I hope it helps you too.
If your osteopath agrees for you to try the slippery elm bark - I would recommend you take in powdered form as it's much more effective because as you drink it down, it coats the whole intestinal tract. I take about 1 1/2 teaspoons mixed in about 1-2 oz. of water, then add the VSL into it, I mix it thoroughly using the back of the spoon to "mash" the lumps out against the glass, and drink it down. If you let it sit too long, it will become very thick and hard to drink, so then you'll need to add more water to it.
Let me know how it works out for you.
I hope you feel better soon.