From all the reading and research I have done it sounds like parasites (particulary giardia). I have just finished a liver/colon/kidney cleanse and still have gas too. This was only a 12 day program that I have done several times in the past (Wild Rose herbal detox). I don't feel as though this program was deep enough and it does not kill parasites. So I have decided to try the Blessed Herbs colon and internal cleanse program. I just ordered it yesterday so I cannot give you feedback on i,t but from others on this site and elsewhere it looks good and very thorough. Here is some links to further cleanses you could try and more info on parasites and the symptoms they cause...Good luck on your cleansing journey!!

This is blog by "lovey" that I found informative:
http://www.curezone.com/blogs/f.asp?f=225&t=57667

http://www.blessedherbs.com

http://www.drnatura.com

The author Dr. Hulda Clark has a great book called "The Cure for all Diseases":
http://www.drclark.net

You could also try searching Amozon.com for books on parasites and bowel/colon cleanses. There are lots of books out there. I search here to find them and then check my local library for them...Good luck!!