If the bugger is hanging out at the in the sigmoid then you should be able to get it with an enema infusion.

First do a ginger tea enema to clear gas, that alone might get it but if not then follow with either strong coffee enema, diluted eucalyptus oil, fennel tea, or any of the medicated enemas. Maybe you could take some cayenne from the top end a few hours beforehand.

Herbs are great for treating things up higher in the digestive tract. Many of them lose their potency by the time they reach the lower colon.

I think you could do a triple attack by adding in castor oil poultice over the sigmoid region in combination with the other methods.

If your blood Sugar isn't too bad you could try a few days of master cleanse with a lot of cayenne in the drinks in combination with enema.