There are plenty of pictures of parasites here on CureZone and all over the 'net, I haven't heard of one that looks like you describe but the world is teeming with little critters I don't know about. :) So check the pictures and see if yours comes up.
If it does, start on a parasite program right away. Just the walnut is not enough, you need full-spectrum herbs.
If you can't verify it is a parasite, wait until you find another one and get it analyzed. Go on with colon cleansing, liver flushing, and watch carefully.