Welcome to HealingWell!
I do not take Amitiza, however, I have read that it causes upset stomach. How long have you been taking it? Usually it takes about
a week to get used to.
Here's a good site with brief info on it: about Amitiza
Here are a couple links to threads that have talked about Amitiza, maybe they will help:
Has anyone tried AMITIZA ?
Has anyone tried Amitiza yet?
Hopefully others will be around soon who have tried it and can give you some info.
Have you tried anything else? How about Miralax?