You will find many places where castor oil is used topically to reduce the
swelling of lymph nodes. Here's but one place that suggests it.
http://www.juniperandsage.com/oils/castor-oil.php
I would also use castor oil packs on your abdomen because that flushes the
entire lymph system. You can learn more about all this at the CZ castor
oil forum.
Here's a site that explains how to make a castor oil pack. I find that
cotton flannel is just as good as wool.