Many players have reported difficulties with finding Foulbelly, even with add-ons that show his location on the map. This has to do with the fact that he is found deep inside a cave, with the entrance being right west of The Circle of Elements.Turn towards the Alliance keep if you are in the middle of the Circle of Elements, and you really can't miss the entrance. Also see the screenshot below for a view of it.
Enter this cave, and when you get to the main room go to the right path. Follow this to get to the very end of the cave, and this is where you will find Foulbelly.
|Cave entrance for finding Foulbelly.|