My theory is that you are getting relief because of its anti-anxiety/depression effects... so i will suggest you first try SSRI and if they dont work then you should go with Anti-psychotics.. There are high chances that SSRI will work for you... PWS have high dopamine because of stuttering itself, so if SSRI helped you then that dopamine will be on its base level anyways without zyprexa you can also check my thread r/StutterMedication , that i created where i compiled all the success stories of people who got relieve from stuttering using these medications... Right now its too early for you but maybe after 6 months please share your story as well on that thread...i am compiling long term users