Have you tried Pau d'arco tea, I am a big believer in the tea for anything related to regularity and cleansing. ( also Cancer, see other postings I have made over the years), I still drink a minimum of two cups per day and up it if i ever feel any stomach upset, gas or irregularity and it straightens me out right away. You should purchase the raw bark and brew it yourself as a decoction ( so much more benefit than just getting the teabags and infusing). Mine comes from http://www.herb-care.com
and is very high quality, but where ever you buy make sure you get the right species and cut it makes a bid difference, I tried some once that was like wood shavings and it tasted so much weaker than the good stuff which is in a fine grind almost like coffee grounds, Tabebuia Avellanedae/Impetiginosa is the species you should look for as it has the most health benefits. There are many types of Pau d'arco so you have to make sure you are getting the right one.
Tip: The tea is also good used topically for rashes etc. I have used the grinds in a poultice with great success.